JP7449362B2 - Electrolytic cell and electrolytic cell manufacturing method - Google Patents

Description

The present invention relates to an electrolytic cell and a method for manufacturing the electrolytic cell.

In the electrolysis of aqueous alkali metal chloride solutions such as salt solutions, and the electrolysis of water (hereinafter collectively referred to as "electrolysis"), an electrolytic cell equipped with a diaphragm, more specifically an ion exchange membrane or a microporous membrane, is used. The method used is being used. This electrolytic cell often includes a large number of electrolytic cells connected in series therein. Electrolysis is performed with a diaphragm interposed between each electrolytic cell. In an electrolytic cell, a cathode chamber having a cathode and an anode chamber having an anode are arranged back to back through a partition wall (rear plate) or through pressing by press pressure, bolt tightening, or the like.
Conventionally, the anode and cathode used in these electrolytic cells are fixed to the anode chamber and cathode chamber of the electrolytic cell by methods such as welding or folding, and then stored and transported to a customer's site. On the other hand, the diaphragm itself is stored and transported to the customer's site while being wrapped around a vinyl chloride pipe or the like. At the customer's site, the electrolytic cell is assembled by arranging the electrolytic cells on the electrolytic tank frame and sandwiching the diaphragm between the electrolytic cells. In this manner, electrolytic cells are manufactured and electrolytic cells are assembled at the customer's site. As structures applicable to such electrolytic cells, Patent Documents 1 and 2 disclose structures in which a diaphragm and an electrode are integrated.

In addition, in a conventional electrolytic cell, if an anode, a diaphragm, and a cathode are simply arranged in this order for each electrolytic cell, which is a constituent unit of the electrolytic cell, due to its structure, a distance of about 1 mm at most will occur between the cathode and the anode. In particular, the electrolysis voltage tends to increase due to the gap that exists between the diaphragm and the cathode acting as resistance (hereinafter, conventional electrolytic cells with such a gap are also referred to as "narrow gap electrolytic cells"). ). In view of this problem, an electrolytic cell in which an anode and a cathode are brought into close contact with a diaphragm to eliminate a gap (hereinafter also referred to as a "zero-gap electrolytic cell") has been developed in order to lower the electrolytic voltage. In addition, in this regard, methods have been proposed for modifying narrow-gap electrolyzers, that is, methods for manufacturing zero-gap electrolyzers by modifying electrolytic cells used in narrow-gap electrolyzers (e.g. , see Patent Document 3).

Japanese Unexamined Patent Publication No. 58-048686 Japanese Unexamined Patent Publication No. 55-148775 Patent No. 5047265

(First purpose)
When electrolysis operation is started and continued, each part deteriorates due to various factors and the electrolysis performance decreases, and at some point each part must be replaced. The diaphragm can be replaced relatively easily by pulling it out from between the electrolytic cells and inserting a new diaphragm. On the other hand, since the anode and cathode are fixed to the electrolytic cell, when replacing the electrode, the electrolytic cell is removed from the electrolytic tank, transported to a dedicated renewal factory, the welding and other fixings are removed, the old electrode is stripped off, and the new electrode is replaced. There is a problem in that it requires extremely complicated work to install, fix using methods such as welding, transport to the electrolytic plant, and return to the electrolytic cell. Here, it is conceivable to use the structure described in Patent Documents 1 and 2 in which the diaphragm and the electrode are integrated by thermocompression bonding, but this structure is relatively easy to construct at the laboratory level. However, it is not easy to manufacture it to fit an actual commercial size electrolytic cell (for example, 1.5 m long and 3 m wide). Moreover, even when the structure is used, the above-mentioned complicated operations are unavoidable.
On the other hand, in view of the above-mentioned problems, it may be possible to renew the deteriorated electrode without removing it by inserting a new electrolysis electrode between the existing electrode and the existing diaphragm. Here, in the case of a so-called zero-gap electrolytic cell in which a diaphragm and a cathode are in contact, the cathode is structured to maintain a zero gap by being pressed in the direction toward the diaphragm and anode by an elastic body. As the body deteriorates (loses sufficient elasticity to maintain zero gap), the elastic body must be replaced with a new one before performing the renewal operation described above, and due to the structure of the electrolyzer, When replacing the elastic body, the existing electrode must be removed once. Such operations can also be said to be complicated.
The present invention has been made in view of the problems of the above-mentioned prior art, and provides a method for manufacturing an electrolytic cell and a structure corresponding thereto, which can improve work efficiency when replacing parts in a zero-gap electrolytic cell. The first object is to provide an electrolytic cell equipped with the following.

(Second purpose)
Furthermore, according to the method described in Patent Document 3, when modifying a narrow gap electrolytic cell, by sequentially installing a cushion mat layer and a new cathode in the gap, the existing narrow gap electrolytic cell It is said that a zero-gap electrolytic cell can be manufactured easily and inexpensively while maintaining the same components. On the other hand, when carrying out the above modification based on a narrow gap electrolytic cell that has already been put into operation, it is assumed that the existing members in the narrow gap electrolytic cell may have deteriorated. According to the method described in Patent Document 3, since a new cathode is installed, the performance as a cathode member is updated even if the existing cathode has deteriorated. If the engine has been operated repeatedly, the existing diaphragm may also have deteriorated. In that case, there is a possibility that the resulting electrolytic performance will not be sufficient just by making the gap zero by the method described in Patent Document 3. Since an electrolytic cell normally includes a large number of electrolytic cells, which are its constituent units, if even one member of the constituent units deteriorates, the effect is likely to become apparent.
The present invention has been made in view of the above problems, and is a method for manufacturing a zero-gap electrolytic cell by modifying an electrolytic cell used in a narrow-gap electrolytic cell. A second object of the present invention is to provide a method for manufacturing an electrolytic cell that can update the performance of the cathode and diaphragm, and also has excellent work efficiency, and an electrolytic cell having a structure corresponding thereto.

As a result of intensive studies to achieve the first objective, the inventors of the present invention found that, instead of removing the existing elastic body in the existing electrolytic cell, by placing a new elastic body in the existing electrolytic cell, The inventors have discovered that the above problems can be solved, and have completed the present invention.
That is, the present invention includes the following aspects.
[1]
an anode;
a cathode facing the anode;
a diaphragm disposed between the anode and the cathode;
a first elastic body that presses the cathode in a direction toward the anode;
a first electrolytic electrode disposed between the diaphragm and the cathode;
a second elastic body disposed between the first electrolysis electrode and the cathode and pressing the first electrolysis electrode in a direction toward the anode;
Equipped with
The first electrolysis electrode functions as a cathode electrode,
An electrolytic cell in which the first electrolysis electrode, the second elastic body, the cathode, and the first elastic body are electrically connected.
[2]
The electrolytic cell according to [1], wherein the second elastic body has a thickness greater than the first elastic body.
[3]
The electrolytic cell according to [1] or [2], wherein the normal surface pressure of the second elastic body is larger than the normal surface pressure of the first elastic body.
[4]
further comprising a second electrolysis electrode disposed between the anode and the diaphragm,
The second electrolysis electrode functions as an anode electrode,
The electrolytic cell according to any one of [1] to [3], wherein the second electrolysis electrode and the anode are electrically connected.
[5]
From an existing electrolytic cell comprising an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, and a first elastic body that presses the cathode in a direction toward the anode. , a method for manufacturing a new electrolytic cell, comprising:
In the existing electrolytic cell, a step of disposing a first electrolysis electrode between the diaphragm and the cathode, and disposing a second elastic body between the first electrolysis electrode and the cathode. (A) includes;
the second elastic body presses the first electrolysis electrode in a direction toward the anode;
The first electrolysis electrode functions as a cathode electrode,
A method for manufacturing an electrolytic cell, wherein the first electrolysis electrode, the second elastic body, the cathode, and the first elastic body are electrically connected.
[6]
The method for manufacturing an electrolytic cell according to [5], wherein the thickness of the second elastic body is greater than the thickness of the first elastic body.
[7]
The method for manufacturing an electrolytic cell according to [5] or [6], wherein the normal surface pressure of the second elastic body is greater than the normal surface pressure of the first elastic body.
[8]
further comprising a step (B) of disposing a second electrolysis electrode between the anode and the diaphragm,
The second electrolysis electrode functions as an anode electrode,
The method for manufacturing an electrolytic cell according to any one of [5] to [7], wherein the second electrolysis electrode and the anode are electrically connected.
[9]
The step (A) includes a sub-step (a1) of removing the diaphragm, and after the sub-step (a1), a laminate including a new diaphragm and the first electrolytic electrode is removed from the second electrode. The method for manufacturing an electrolytic cell according to any one of [5] to [7], including the substep (a2) of disposing the elastic body between the elastic body and the anode.
[10]
The laminate further includes a second electrolysis electrode,
The second electrolysis electrode functions as an anode electrode,
The method for manufacturing an electrolytic cell according to [9], wherein the second electrolysis electrode and the anode are electrically connected.

In addition, as a result of intensive studies to achieve the second objective, the present inventors have developed a new method for manufacturing a zero-gap electrolytic cell by modifying an electrolytic cell used in a narrow-gap electrolytic cell. The inventors have discovered that the above problem can be solved by disposing a laminate including a diaphragm and an electrode for electrolysis, and have completed the present invention.
That is, the present invention includes the following aspects.
[11]
A new electrolytic cell is manufactured from an existing electrolytic cell including an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, and a support that directly supports the cathode. A method for
In the existing electrolytic cell, the diaphragm is replaced with a laminate including a new diaphragm and a first electrolytic electrode, and an elastic body is arranged between the first electrolytic electrode and the cathode. including step (A);
the elastic body presses the first electrolysis electrode in a direction toward the anode,
The thickness of the first electrolysis electrode is 120 μm or less,
A method for manufacturing an electrolytic cell, wherein the first electrolysis electrode, the elastic body, the cathode, and the support are electrically connected.
[12]
The laminate further includes a second electrolysis electrode,
The second electrolysis electrode functions as an anode electrode,
The method for manufacturing an electrolytic cell according to [11], wherein the second electrolysis electrode and the anode are electrically connected.
[13]
an anode;
a cathode facing the anode;
a diaphragm disposed between the anode and the cathode;
a first electrolytic electrode disposed between the diaphragm and the cathode;
a second electrolysis electrode disposed between the anode and the diaphragm;
an elastic body disposed between the first electrolysis electrode and the cathode and pressing the first electrolysis electrode in a direction toward the anode;
a support that directly supports the cathode;
Equipped with
The first electrolysis electrode functions as a cathode electrode,
The second electrolysis electrode functions as an anode electrode,
The thickness of the first electrolysis electrode is 120 μm or less,
The first electrolysis electrode, the elastic body, the cathode, and the support are electrically connected,
An electrolytic cell in which the second electrolysis electrode and the anode are electrically connected.
[14]
A new electrolytic cell is manufactured from an existing electrolytic cell comprising an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, and a support that directly supports the cathode. A method for
In the existing electrolysis cell , the diaphragm is replaced with a laminate including a new diaphragm and a first electrolysis electrode, and an elastic body is arranged between the first electrolysis electrode and the cathode. including step (A);
the elastic body presses the first electrolysis electrode in a direction toward the anode,
The thickness of the first electrolysis electrode is 120 μm or less,
A method for manufacturing an electrolytic cell, wherein the first electrolytic electrode, the elastic body, the cathode, and the support are electrically connected.
[15]
The laminate further includes a second electrolysis electrode,
The second electrolysis electrode functions as an anode electrode,
The method for manufacturing an electrolytic cell according to [14], wherein the second electrolytic electrode and the anode are electrically connected.
[16]
an anode;
a cathode facing the anode;
a diaphragm disposed between the anode and the cathode;
a first electrolysis electrode disposed between the diaphragm and the cathode;
a second electrolysis electrode disposed between the anode and the diaphragm;
an elastic body disposed between the first electrolysis electrode and the cathode and pressing the first electrolysis electrode in a direction toward the anode;
a support that directly supports the cathode;
Equipped with
The first electrolysis electrode functions as a cathode electrode,
The second electrolysis electrode functions as an anode electrode,
The thickness of the first electrolysis electrode is 120 μm or less,
The first electrolysis electrode, the elastic body, the cathode, and the support are electrically connected,
An electrolysis cell, wherein the second electrolysis electrode and the anode are electrically connected.
[17]
An electrolytic cell comprising the electrolytic cell according to [16].

According to one aspect of the present invention, it is possible to provide a method for manufacturing an electrolytic cell that can improve work efficiency during electrode renewal in an electrolytic cell, and an electrolytic cell having a structure corresponding thereto.
Further, according to another aspect of the present invention, in a method for manufacturing a zero-gap electrolytic cell by modifying an electrolytic cell used in a narrow-gap electrolytic cell, in addition to achieving a zero gap, the existing cathode and It is possible to provide a method for manufacturing an electrolytic cell that can update the performance of the diaphragm and also has excellent work efficiency, and an electrolytic cell that has a structure corresponding thereto.

FIG. 1 is a schematic cross-sectional view of an electrolytic cell according to a first embodiment. FIG. 2 is a schematic cross-sectional view showing a state in which two electrolytic cells are connected in series in the existing electrolytic cell according to the first embodiment. FIG. 3 is a schematic cross-sectional view illustrating a state in which two electrolytic cells are connected in series in the electrolytic cell according to the first embodiment. FIG. 4 is a schematic diagram of the electrolytic cell according to the first embodiment. FIG. 5 is a schematic perspective view showing the process of assembling the electrolytic cell according to the first embodiment. FIG. 6 is a schematic cross-sectional view of a reverse current absorber that can be included in the electrolytic cell in this embodiment. FIG. 7 is a schematic cross-sectional view of the electrolysis electrode in this embodiment. FIG. 8 is a schematic cross-sectional view illustrating the structure of the ion exchange membrane in this embodiment. FIG. 9 is a schematic diagram for explaining the aperture ratio of the reinforcing core material that constitutes the ion exchange membrane in this embodiment. FIG. 10 is a schematic diagram for explaining a method of forming communication holes in an ion exchange membrane. FIG. 11 is an explanatory diagram illustrating one aspect of the method for manufacturing an electrolytic cell according to the first embodiment. FIG. 12 is an explanatory diagram illustrating another aspect of the method for manufacturing an electrolytic cell according to the first embodiment. FIG. 13 is an explanatory diagram illustrating still another aspect of the method for manufacturing an electrolytic cell according to the first embodiment. FIG. 14 is an explanatory diagram illustrating yet another aspect of the method for manufacturing an electrolytic cell according to the first embodiment. FIG. 15 is a schematic cross-sectional view of the electrolytic cell according to the second embodiment. FIG. 16 is a schematic diagram of an electrolytic cell according to the second embodiment. FIG. 17 is a schematic perspective view showing the process of assembling the electrolytic cell according to the second embodiment. FIG. 18 is a schematic diagram of members used in the method for manufacturing an electrolytic cell according to the second embodiment. FIG. 18(A) is a schematic diagram of the elastic body. FIG. 18(B) is a schematic diagram of a laminate of a first electrolytic electrode and a diaphragm. FIG. 18(C) is a schematic diagram of a laminate of a first electrolytic electrode, a diaphragm, and a second electrolytic electrode. FIG. 19 is a schematic cross-sectional view illustrating an electrolytic cell obtained when one aspect of the method for manufacturing an electrolytic cell according to the second embodiment is carried out. FIG. 20 is a schematic cross-sectional view illustrating an electrolytic cell obtained when another aspect of the method for manufacturing an electrolytic cell according to the second embodiment is carried out.

EMBODIMENT OF THE INVENTION Hereinafter, embodiments of the present invention (hereinafter also referred to as the present embodiments) will be described in detail with reference to the drawings as necessary. The following embodiments are examples for explaining the present invention, and the present invention is not limited to the following contents. Further, the attached drawings show an example of the embodiment, and the form is not to be interpreted as being limited to this. The present invention can be implemented with appropriate modifications within the scope of its gist. Note that the positional relationships such as the top, bottom, left, and right in the drawings are based on the positional relationships shown in the drawings unless otherwise specified. The dimensions and proportions of the drawings are not limited to those shown.

<First embodiment>
Here, a first aspect of the present embodiment (hereinafter also referred to as "first embodiment") will be described in detail with reference to FIGS. 1 to 14.

[Electrolytic cell]
The electrolytic cell of the first embodiment (hereinafter, unless otherwise specified, "this embodiment" in the section <First Embodiment> means the first embodiment) includes an anode and an electrode facing the anode. a cathode, a diaphragm disposed between the anode and the cathode, a first elastic body that presses the cathode in a direction toward the anode, and a first elastic body disposed between the diaphragm and the cathode. and a second elastic body disposed between the first electrolysis electrode and the cathode and pressing the first electrolysis electrode in a direction toward the anode. , the first electrolysis electrode functions as a cathode electrode, and the first electrolysis electrode, the second elastic body, the cathode, and the first elastic body are electrically connected.
According to the electrolytic cell having the above configuration, the second elastic body presses the first electrolysis electrode in the direction toward the anode, so the first elastic body deteriorates and maintains the zero gap. Even if the second elastic body loses sufficient elasticity to do so, the elasticity of the second elastic body makes it possible to maintain zero gap, eliminating the need to remove and replace the first elastic body itself. Furthermore, even if the second elastic body deteriorates and loses sufficient elasticity to maintain the zero gap, since the second elastic body is held between adjacent members, The second elastic body itself can be easily replaced with a new one by simply releasing the second elastic body.
In addition, even if the cathode deteriorates, since the first electrolytic electrode functions as a cathode electrode, there is no need to remove and replace the cathode itself. Furthermore, even if the first electrolytic electrode deteriorates and the electrolytic performance decreases, since the first electrolytic electrode is sandwiched between adjacent members, it is easy to remove the sandwiching. The first electrolysis electrode can be replaced with a new one.
Therefore, according to the electrolytic cell of this embodiment, it is possible to avoid complicated work when updating the electrodes in the electrolytic cell.
In this embodiment, a combination of an anode chamber containing an anode and a cathode chamber containing a cathode is referred to as an electrolytic cell, and each member will be described in detail below.

[Electrolytic cell]
First, an electrolytic cell that can be used as a structural unit of the electrolytic cell of this embodiment will be described. FIG. 1 is a cross-sectional view of an electrolytic cell 50. As shown in FIG.
The electrolytic cell 50 includes an anode chamber 60, a cathode chamber 70, a partition 80 installed between the anode chamber 60 and the cathode chamber 70, an anode 11 installed in the anode chamber 60, and an anode 11 installed in the cathode chamber 70. A cathode 21 is provided. If necessary, a reverse current absorber 18 may be provided inside the cathode chamber. The anode 11 and cathode 21 belonging to one electrolytic cell 50 are electrically connected to each other. The electrolytic cell 50 can also be said to include the following cathode structure. The cathode structure 90 includes a cathode chamber 70, a cathode 21 installed in the cathode chamber 70, and a reverse current absorber 18 installed in the cathode chamber 70, and the reverse current absorber 18 is shown in FIG. As shown, it has a base material 18a and a reverse current absorption layer 18b formed on the base material 18a, and the cathode 21 and the reverse current absorption layer 18b are electrically connected. The cathode chamber 70 further includes a current collector 23, a support 24 that supports the current collector, and a first elastic body 22 that is a metal elastic body. The first elastic body 22 is installed between the current collector 23 and the cathode 21 . The support body 24 is installed between the current collector 23 and the partition wall 80. Current collector 23 is electrically connected to cathode 21 via first elastic body 22 . The partition 80 is electrically connected to the current collector 23 via the support 24 . Therefore, the partition wall 80, the support body 24, the current collector 23, the first elastic body 22, and the cathode 21 are electrically connected. The cathode 21 and the reverse current absorption layer 18b are electrically connected. The cathode 21 and the reverse current absorption layer may be directly connected, or may be indirectly connected via a current collector, a support, a metal elastic body, a partition, or the like. Preferably, the entire surface of the cathode 21 is coated with a catalyst layer for the reduction reaction. In addition, the form of electrical connection is such that the partition 80 and the support 24, the support 24 and the current collector 23, and the current collector 23 and the first elastic body 22 are directly attached, respectively, and The cathode 21 may be stacked. Welding or the like can be cited as a method for directly attaching these constituent members to each other. Further, the reverse current absorber 18, the cathode 21, and the current collector 23 may be collectively referred to as the cathode structure 90.

FIG. 2 is a cross-sectional view of two adjacent electrolytic cells 50 in the electrolytic cell before the electrolytic cell of this embodiment is assembled. FIG. 3 is a sectional view of two adjacent electrolytic cells 50 in the electrolytic bath 4 of this embodiment. FIG. 4 shows the electrolytic cell 4 of this embodiment. FIG. 5 shows the process of assembling the electrolytic cell 4.

As shown in FIG. 2, an electrolytic cell 50, a cation exchange membrane 51, and an electrolytic cell 50 are arranged in series in this order. In FIG. 2, a cation exchange membrane 51 is arranged between the anode chamber of one electrolytic cell 50 and the cathode chamber of the other electrolytic cell 50 among two adjacent electrolytic cells. That is, the anode chamber 60 of the electrolytic cell 50 and the cathode chamber 70 of the adjacent electrolytic cell 50 are separated by the cation exchange membrane 51. As shown in FIG. 4, the electrolytic cell 4 is composed of a plurality of electrolytic cells 50 connected in series via a cation exchange membrane 51. That is, the electrolytic cell 4 is a bipolar electrolytic cell including a plurality of electrolytic cells 50 arranged in series and a cation exchange membrane 51 arranged between adjacent electrolytic cells 50. As shown in FIG. 5, the electrolytic cell 4 is assembled by arranging a plurality of electrolytic cells 50 in series via a cation exchange membrane 51 and connecting them by a press 5.

The structure of the electrolytic cell of this embodiment will be explained using FIG. 3(A). As shown in FIG. 3(A), in the electrolytic cell 4, a first electrolytic electrode 53 is arranged between the cation exchange membrane 51 and the electrolytic cell 50 on the left side thereof. That is, the first electrolysis electrode 53 is disposed between the cathode 21 and the cation exchange membrane 51, and functions as a cathode electrode. Furthermore, as shown in FIG. 3(A), a second elastic body 22' is disposed between the first electrolysis electrode 53 and the cathode 21.
In this way, in the electrolytic cell of this embodiment, the second elastic body 22' presses the first electrolysis electrode 53 in the direction toward the anode 11, so the first elastic body 22 is deteriorated. Even if the second elastic body 22' loses sufficient elasticity to maintain the zero gap, the elasticity of the second elastic body 22' makes it possible to maintain the zero gap, eliminating the need to remove and replace the first elastic body 22 itself. disappears. Furthermore, even if the second elastic body 22' deteriorates and loses sufficient elasticity to maintain zero gap, the second elastic body 22' is held between adjacent members. Therefore, the second elastic body itself can be easily replaced with a new one by simply releasing the clamping.
In addition, even if the cathode 21 deteriorates, since the first electrolytic electrode 53 functions as a cathode electrode, there is no need to remove or replace the cathode 21 itself. Furthermore, even if the first electrolytic electrode 53 deteriorates and the electrolytic performance decreases, since the first electrolytic electrode 53 is sandwiched between adjacent members, it is only necessary to release the sandwiching. The first electrolysis electrode can be easily replaced with a new one.

A preferable structure of the electrolytic cell of this embodiment will be explained using FIG. 3(B). As shown in FIG. 3(B), in the electrolytic cell 4, a first electrolytic electrode 53, a cation exchange membrane 51, and a second electrode are connected between the cation exchange membrane 51 and the electrolysis cell 50 on the left side. A laminate 54 including an electrolytic electrode 53' is arranged. That is, the first electrolysis electrode 53 is arranged between the cathode 21 and the cation exchange membrane 51 and functions as a cathode electrode, while the second electrolysis electrode 53' is arranged between the anode 11 and the cation exchange membrane 51. 51, and functions as an anode electrode. Furthermore, as shown in FIG. 3(B), a second elastic body 22' is disposed between the first electrolysis electrode 53 and the cathode 21.
Even in such an electrolytic cell, the second elastic body 22' presses the first electrolysis electrode 53 in the direction toward the anode 11, so the first elastic body 22 deteriorates and the zero gap is closed. Even if sufficient elasticity is lost to maintain the zero gap, the elasticity of the second elastic body 22' makes it possible to maintain the zero gap, eliminating the need to remove and replace the first elastic body 22 itself. Furthermore, even if the second elastic body 22' deteriorates and loses sufficient elasticity to maintain zero gap, the second elastic body 22' is held between adjacent members. Therefore, the second elastic body itself can be easily replaced with a new one by simply releasing the clamping.
In addition, even if the cathode 21 deteriorates, since the first electrolytic electrode 53 functions as a cathode electrode, there is no need to remove or replace the cathode 21 itself. Furthermore, even if the first electrolytic electrode 53 deteriorates and the electrolytic performance decreases, since the first electrolytic electrode 53 is sandwiched between adjacent members, it is only necessary to release the sandwiching. The first electrolysis electrode can be easily replaced with a new one.
Furthermore, even if the anode 11 deteriorates, the second electrolysis electrode 53' functions as the anode electrode, so there is no need to remove or replace the anode 11 itself. Furthermore, even if the second electrolytic electrode 53' deteriorates and the electrolytic performance decreases, since the second electrolytic electrode 53' is sandwiched between adjacent members, the sandwiching can be released. The second electrolysis electrode can be easily replaced with a new one by simply doing the following.

Electrolytic cell 4 has an anode terminal 7 and a cathode terminal 6 connected to a power source. The anode 11 of the electrolytic cell 50 located at the end of the plurality of electrolytic cells 50 connected in series in the electrolytic cell 4 is electrically connected to the anode terminal 7 . Among the plurality of electrolytic cells 50 connected in series in the electrolytic cell 4 , the cathode 21 of the electrolytic cell located at the end opposite to the anode terminal 7 is electrically connected to the cathode terminal 6 . Current during electrolysis flows from the anode terminal 7 side toward the cathode terminal 6 via the anode and cathode of each electrolysis cell 50. Note that an electrolytic cell having only an anode chamber (anode terminal cell) and an electrolytic cell having only a cathode chamber (cathode terminal cell) may be arranged at both ends of the connected electrolytic cells 50. In this case, the anode terminal 7 is connected to the anode terminal cell arranged at one end, and the cathode terminal 6 is connected to the cathode terminal cell arranged at the other end.

When electrolyzing salt water, each anode chamber 60 is supplied with salt water, and the cathode chamber 70 is supplied with pure water or a low concentration aqueous sodium hydroxide solution. Each liquid is supplied to each electrolytic cell 50 from an electrolyte supply pipe (not shown) via an electrolyte supply hose (not shown). Further, the electrolytic solution and the products of electrolysis are recovered from an electrolytic solution recovery pipe (not shown). In electrolysis, sodium ions in salt water move from the anode chamber 60 of one electrolytic cell 50 to the cathode chamber 70 of the adjacent electrolytic cell 50 through the cation exchange membrane 51. Therefore, the current during electrolysis flows along the direction in which the electrolytic cells 50 are connected in series. That is, the current flows from the anode chamber 60 to the cathode chamber 70 via the cation exchange membrane 51. With the electrolysis of salt water, chlorine gas is generated on the anode 11 side, and sodium hydroxide (solute) and hydrogen gas are generated on the cathode 21 side.

(Anode chamber)
The anode chamber 60 has an anode 11 or an anode power supply body 11 . The power supply here means a deteriorated electrode (that is, an existing electrode), an electrode without catalyst coating, or the like. When the electrode for electrolysis in this embodiment is inserted into the anode side, 11 functions as an anode power supply body. When the electrode for electrolysis in this embodiment is not inserted into the anode side, 11 functions as an anode. Further, the anode chamber 60 is disposed above the anode side electrolyte supply section that supplies the electrolyte to the anode chamber 60 and the anode side electrolyte supply section, and is disposed approximately parallel or obliquely to the partition wall 80. It is preferable to have a baffle plate and an anode-side gas-liquid separation section that is arranged above the baffle plate and separates gas from the electrolyte mixed with gas.

(anode)
When the electrode for electrolysis in this embodiment is not inserted into the anode side, the anode 11 is provided within the frame of the anode chamber 60 (that is, the anode frame). As the anode 11, a metal electrode such as so-called DSA (registered trademark) can be used. DSA is a titanium-based electrode whose surface is coated with an oxide containing ruthenium, iridium, and titanium.
As for the shape, any of punched metal, nonwoven fabric, foamed metal, expanded metal, porous metal foil formed by electroforming, so-called woven mesh made by knitting metal wires, etc. can be used.

(Anode power supply)
When the electrode for electrolysis in this embodiment is inserted into the anode side, the anode power supply body 11 is provided within the frame of the anode chamber 60. As the anode power supply body 11, a metal electrode such as so-called DSA (registered trademark) can be used, or titanium without catalyst coating can also be used. Furthermore, DSA with a thinner catalyst coating can also be used. Furthermore, a used anode can also be used.
As for the shape, any of punched metal, nonwoven fabric, foamed metal, expanded metal, porous metal foil formed by electroforming, so-called woven mesh made by knitting metal wires, etc. can be used.

(Anode side electrolyte supply section)
The anode side electrolyte supply section supplies an electrolyte to the anode chamber 60 and is connected to an electrolyte supply pipe. The anode side electrolyte supply section is preferably arranged below the anode chamber 60. As the anode-side electrolyte supply section, for example, a pipe (dispersion pipe) having an opening formed on its surface can be used. More preferably, such a pipe is arranged along the surface of the anode 11 and parallel to the bottom 19 of the electrolytic cell. This pipe is connected to an electrolytic solution supply pipe (liquid supply nozzle) that supplies electrolytic solution into the electrolytic cell 50. The electrolytic solution supplied from the liquid supply nozzle is conveyed into the electrolytic cell 50 by a pipe, and is supplied into the anode chamber 60 from an opening provided on the surface of the pipe. It is preferable to arrange the pipe along the surface of the anode 11 in parallel to the bottom 19 of the electrolytic cell, since the electrolyte can be uniformly supplied into the anode chamber 60.

(Anode side gas-liquid separation section)
It is preferable that the anode side gas-liquid separation section is arranged above the baffle plate. During electrolysis, the anode side gas-liquid separation section has a function of separating generated gas such as chlorine gas and electrolyte solution. Note that, unless otherwise specified, "upper" means the upper direction in the electrolytic cell 50 in FIG. 1, and "downward" means the lower direction in the electrolytic cell 50 in FIG.

During electrolysis, when the generated gas and electrolyte generated in the electrolytic cell 50 become a mixed phase (gas-liquid mixed phase) and are discharged from the system, vibrations occur due to pressure fluctuations inside the electrolytic cell 50, causing physical damage to the ion exchange membrane. May cause damage. In order to suppress this, it is preferable that the electrolytic cell 50 in this embodiment is provided with an anode side gas-liquid separation section for separating gas and liquid. It is preferable that a defoaming plate for eliminating air bubbles is installed in the anode side gas-liquid separation section. When the gas-liquid multiphase flow passes through the defoaming plate, the bubbles burst and can be separated into the electrolyte and the gas. As a result, vibration during electrolysis can be prevented.

(baffle board)
It is preferable that the baffle plate is disposed above the anode side electrolyte supply section and disposed approximately parallel or obliquely to the partition wall 80. The baffle plate is a partition plate that controls the flow of electrolyte in the anode chamber 60. By providing the baffle plate, the electrolytic solution (salt water, etc.) can be internally circulated in the anode chamber 60 and its concentration can be made uniform. In order to cause internal circulation, the baffle plate is preferably arranged to separate the space near the anode 11 from the space near the partition 80. From this point of view, it is preferable that the baffle plate be provided so as to face each surface of the anode 11 and the partition wall 80. In the space near the anode partitioned by the baffle plate, as electrolysis progresses, the electrolyte concentration (salt water concentration) decreases and generated gases such as chlorine gas are generated. This creates a difference in the specific gravity of gas and liquid between the space near the anode 11 partitioned by the baffle plate and the space near the partition wall 80. Utilizing this, internal circulation of the electrolyte in the anode chamber 60 can be promoted and the concentration distribution of the electrolyte in the anode chamber 60 can be made more uniform.

Although not shown in FIG. 1, a current collector may be separately provided inside the anode chamber 60. Such a current collector can also be made of the same material and structure as the current collector of the cathode chamber, which will be described later. Further, in the anode chamber 60, the anode 11 itself can also function as a current collector.

(bulkhead)
The partition wall 80 is arranged between the anode chamber 60 and the cathode chamber 70. The partition wall 80 is sometimes called a separator and partitions the anode chamber 60 and the cathode chamber 70. As the partition wall 80, a well-known separator for electrolysis can be used, such as a partition wall in which a plate made of nickel on the cathode side and titanium on the anode side is welded.

(Cathode chamber)
In the cathode chamber 70, when the electrode for electrolysis in this embodiment is inserted into the cathode side, 21 functions as a cathode power supply body, and when the electrode for electrolysis in this embodiment is not inserted into the cathode side, 21 functions as a cathode power supply body. Functions as a cathode. When a reverse current absorber is provided, the cathode or cathode power supply body 21 and the reverse current absorber are electrically connected. Further, like the anode chamber 60, the cathode chamber 70 preferably has a cathode-side electrolyte supply section and a cathode-side gas-liquid separation section. It should be noted that, among the parts constituting the cathode chamber 70, the descriptions of the parts similar to the parts constituting the anode chamber 60 will be omitted.

(cathode)
When the electrode for electrolysis in this embodiment is not inserted into the cathode side, the cathode 21 is provided within the frame of the cathode chamber 70 (that is, the cathode frame). It is preferable that the cathode 21 has a nickel base material and a catalyst layer covering the nickel base material. Components of the catalyst layer on the nickel base material include Ru, C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Examples include metals such as Dy, Ho, Er, Tm, Yb, and Lu, and oxides or hydroxides of the metals. Examples of methods for forming the catalyst layer include plating, alloy plating, dispersion/composite plating, CVD, PVD, thermal decomposition, and thermal spraying. These methods may be combined. The catalyst layer may have multiple layers and multiple elements as necessary. Further, the cathode 21 may be subjected to a reduction treatment if necessary. Note that as the base material of the cathode 21, nickel, nickel alloy, iron, or stainless steel plated with nickel may be used.
As for the shape, any of punched metal, nonwoven fabric, foamed metal, expanded metal, porous metal foil formed by electroforming, so-called woven mesh made by knitting metal wires, etc. can be used.

(Cathode feeder)
When the electrode for electrolysis in this embodiment is inserted into the cathode side, the cathode power supply body 21 is provided within the frame of the cathode chamber 70 . The cathode power supply body 21 may be coated with a catalyst component. The catalyst component may be one that was originally used as a cathode and remains. Components of the catalyst layer include Ru, C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Rh, Pd, Ag. , Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er , Tm, Yb, Lu, and oxides or hydroxides of the metals. Examples of methods for forming the catalyst layer include plating, alloy plating, dispersion/composite plating, CVD, PVD, thermal decomposition, and thermal spraying. These methods may be combined. The catalyst layer may have multiple layers and multiple elements as necessary. Alternatively, nickel, nickel alloy, iron, or stainless steel without catalyst coating may be plated with nickel. Note that as the base material of the cathode power supply body 21, nickel, nickel alloy, iron, or stainless steel plated with nickel may be used.
As for the shape, any of punched metal, nonwoven fabric, foamed metal, expanded metal, porous metal foil formed by electroforming, so-called woven mesh made by knitting metal wires, etc. can be used.

(reverse current absorption layer)
A material having a redox potential less noble than the redox potential of the element for the catalyst layer of the cathode described above can be selected as the material for the reverse current absorbing layer. Examples include nickel and iron.

(current collector)
Preferably, the cathode chamber 70 includes a current collector 23 . This increases the current collection effect. In this embodiment, the current collector 23 is a porous plate, and is preferably arranged substantially parallel to the surface of the cathode 21.

The current collector 23 is preferably made of an electrically conductive metal such as nickel, iron, copper, silver, or titanium. The current collector 23 may be a mixture, alloy, or composite oxide of these metals. Note that the current collector 23 may have any shape as long as it functions as a current collector, and may be plate-like or mesh-like.

(elastic body)
By installing the first elastic body 22 between the current collector 23 and the cathode 21, each cathode 21 of the plurality of electrolytic cells 50 connected in series is pressed against the cation exchange membrane 51, and each anode 11 and each cathode 21 becomes shorter, and the voltage applied to the entire plurality of electrolytic cells 50 connected in series can be lowered. By lowering the voltage, power consumption can be lowered. Moreover, by installing the first elastic body 22, when the laminate including the electrolytic electrode in this embodiment is installed in an electrolytic cell, the pressing pressure by the first elastic body 22 causes the electrolytic electrode to can be stably maintained in position. However, in this embodiment, it is assumed that the first elastic body 22 deteriorates over time due to long-term operation of the electrolytic cell. That is, the first elastic body 22 may be one that has lost sufficient elasticity to maintain the zero gap due to deterioration. Even if the first elastic body 22 has deteriorated in this way, the zero gap can be maintained due to the elasticity of the second elastic body in this embodiment.

As the first elastic body 22 and the second elastic body 22', a spring member such as a spiral spring or a coil, a cushioning mat, or the like can be used. Further, as the first elastic body 22 and the second elastic body 22', suitable materials can be adopted as appropriate in consideration of the stress of pressing the ion exchange membrane. The first elastic body 22 may be provided on the surface of the current collector 23 on the cathode chamber 70 side, or may be provided on the surface of the partition wall on the anode chamber 60 side. Usually, both chambers are divided so that the cathode chamber 70 is smaller than the anode chamber 60, so from the viewpoint of the strength of the frame, the first elastic body 22 is connected to the current collector 23 of the cathode chamber 70 and the cathode 23. It is preferable to provide it between the two. Further, the first elastic body 22 and the second elastic body 22' are preferably made of an electrically conductive metal such as nickel, iron, copper, silver, or titanium.
In this embodiment, the first elastic body 22 and the second elastic body 22' may have the same shape, material, and physical properties, or may be different in these respects.

In the electrolytic cell of this embodiment, from the viewpoint of effectively preventing loss of the zero-gap structure due to deterioration of the first elastic body, the thickness of the second elastic body is equal to or smaller than that of the first elastic body. It is preferably larger than the thickness. From the same viewpoint as above, it is preferable that the normal surface pressure of the second elastic body is larger than the normal surface pressure of the first elastic body.
Note that the thickness of the first elastic body and the thickness of the second elastic body are not particularly limited, and both can be, for example, 0.1 mm to 15 mm, preferably 0.2 mm to 10 mm, and more preferably is 0.5 mm to 7 mm.
Further, the normal surface pressure of the first elastic body and the normal surface pressure of the second elastic body are not particularly limited, and both can be set to, for example, 30 gf/cm ² to 350 gf/cm ² , preferably 40 to 350 gf/cm 2 . It is 300 gf/cm ² , more preferably 50 to 250 gf/cm ² .

(Support)
Preferably, the cathode chamber 70 includes a support 24 that electrically connects the current collector 23 and the partition 80. This allows current to flow efficiently.

The support body 24 is preferably made of an electrically conductive metal such as nickel, iron, copper, silver, or titanium. Further, the support body 24 may have any shape as long as it can support the current collector 23, and may be a rod shape, a plate shape, or a net shape. The support body 24 is, for example, plate-shaped. The plurality of supports 24 are arranged between the partition wall 80 and the current collector 23. The plurality of supports 24 are arranged so that their respective surfaces are parallel to each other. The support body 24 is arranged substantially perpendicularly to the partition wall 80 and the current collector 23.

(Anode side gasket, cathode side gasket)
The anode side gasket 12 is preferably arranged on the surface of the frame that constitutes the anode chamber 60. The cathode side gasket 13 is preferably arranged on the surface of the frame that constitutes the cathode chamber 70. The electrolytic cells are connected so that the anode side gasket 12 of one electrolytic cell and the cathode side gasket 13 of the adjacent electrolytic cell sandwich the cation exchange membrane 51 (see FIG. 2). These gaskets can provide airtightness to the connection locations when connecting the plurality of electrolytic cells 50 in series via the cation exchange membranes 51.

A gasket is a seal between an ion exchange membrane and an electrolytic cell. A specific example of the gasket is a frame-shaped rubber sheet with an opening formed in the center. Gaskets are required to be resistant to corrosive electrolytes and generated gases, and to be able to be used for long periods of time. Therefore, from the viewpoint of chemical resistance and hardness, vulcanized products of ethylene propylene diene rubber (EPDM rubber), ethylene propylene rubber (EPM rubber), peroxide crosslinked products, etc. are usually used as gaskets. In addition, if necessary, use a gasket whose area that comes into contact with the liquid (liquid contact part) is coated with a fluororesin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA). You can also do it. These gaskets only need to each have an opening so as not to impede the flow of the electrolytic solution, and their shapes are not particularly limited. For example, a frame-shaped gasket is pasted with adhesive or the like along the periphery of each opening of the anode chamber frame constituting the anode chamber 60 or the cathode chamber frame constituting the cathode chamber 70. For example, when two electrolytic cells 50 are connected via the cation exchange membrane 51 (see FIG. 2), each electrolytic cell 50 to which a gasket is attached may be tightened via the cation exchange membrane 51. Thereby, leakage of the electrolytic solution, alkali metal hydroxide, chlorine gas, hydrogen gas, etc. generated by electrolysis to the outside of the electrolytic cell 50 can be suppressed.

[Laminated body]
The electrode for electrolysis in this embodiment can be used as a laminate with a diaphragm such as an ion exchange membrane or a microporous membrane. That is, the laminate in this embodiment may include a first electrolytic electrode and a diaphragm, or may include a first electrolytic electrode, a diaphragm, and a second electrolytic electrode. Good too. Specific examples of the electrolysis electrode and the diaphragm will be described in detail below.

[Electrode for electrolysis]
The electrode for electrolysis in this embodiment is not particularly limited, but is preferably one that can form a laminate with the diaphragm as described above, that is, one that can be integrated with the diaphragm, and is used as a wound body. It is more preferable that there be. The electrolysis electrode may function as a cathode or an anode in the electrolytic cell. Further, the material, shape, physical properties, etc. of the electrode for electrolysis can be appropriately selected in consideration of the steps (A) and (B) in this embodiment described later, the structure of the electrolytic cell, etc. Preferred embodiments of the electrolysis electrode in this embodiment will be described below, but these are merely examples of preferred embodiments for carrying out steps (A) and (B), and electrolysis electrodes other than the embodiments described below may also be used. Can be adopted as appropriate.

The electrode for electrolysis in this embodiment has good handling properties, and has good adhesion to diaphragms such as ion exchange membranes and microporous membranes, power supply bodies (deteriorated electrodes and electrodes without catalyst coating), etc. From the viewpoint of having the following properties, the applied force per unit mass/unit area is preferably 1.6 N/(mg cm ² ) or less, more preferably less than 1.6 N/(mg cm ² ), and It is preferably less than 1.5 N/(mg·cm ² ), even more preferably 1.2 N/mg·cm ² or less, and even more preferably 1.20 N/mg·cm ² or less. It is even more preferably 1.1 N/mg·cm ² or less, even more preferably 1.10 N/mg·cm ² or less, particularly preferably 1.0 N/mg·cm ² or less, and 1.00 N /mg·cm ² or less is particularly preferable.
From the viewpoint of further improving electrolytic performance, it is preferably more than 0.005 N/(mg·cm ² ), more preferably 0.08 N/(mg·cm ² ) or more, and even more preferably 0.1 N/mg. - cm ² or more, more preferably 0.14 N/(mg·cm ² ) or more. From the viewpoint of easy handling in a large size (for example, size 1.5 m x 2.5 m), 0.2 N/(mg·cm ² ) or more is even more preferable.
The above-mentioned force can be controlled within the above range by appropriately adjusting the porosity, electrode thickness, arithmetic mean surface roughness, etc., which will be described later. More specifically, for example, as the porosity increases, the applied force tends to decrease, and as the porosity decreases, the applied force tends to increase.
In addition, it has good handling properties, has good adhesion to diaphragms such as ion exchange membranes and microporous membranes, deteriorated electrodes, and power supply bodies without catalyst coating, and is also economical. , the mass per unit area is preferably 48 mg/cm ² or less, more preferably 30 mg/cm ² or less, even more preferably 20 mg/cm ² or less, and also has handling properties and adhesive properties. From a comprehensive viewpoint including economical efficiency, it is preferable that the amount is 15 mg/cm ² or less. Although the lower limit is not particularly limited, it is, for example, about 1 mg/cm ² .
The mass per unit area can be set within the above range, for example, by appropriately adjusting the porosity, electrode thickness, etc., which will be described later. More specifically, for example, if the thickness is the same, as the porosity increases, the mass per unit area tends to decrease, and as the porosity decreases, the mass per unit area tends to increase. be.

Such force can be measured by the following method (i) or (ii). This force is the value obtained by measuring method (i) (also referred to as "applicable force (1)") and the value obtained by measuring method (ii) (also referred to as "approximate force (2)"). may be the same or different, but any value is preferably less than 1.5 N/mg·cm ² .

[Method (i)]
Inorganic particles and a binder were applied to both sides of a nickel plate (1.2 mm thick, 200 mm square) obtained by blasting with alumina grain number 320 and a perfluorocarbon polymer membrane into which ion exchange groups were introduced. An ion exchange membrane (170 mm square, details of the ion exchange membrane referred to here are as described in Examples) and an electrode sample (130 mm square) were stacked in this order, and the stack was soaked in pure water. After sufficient immersion, excess moisture adhering to the surface of the laminate is removed to obtain a measurement sample. Note that the arithmetic mean surface roughness (Ra) of the nickel plate after blasting is 0.5 to 0.8 μm. A specific method for calculating the arithmetic mean surface roughness (Ra) is as described in Examples.
Under conditions of a temperature of 23 ± 2°C and a relative humidity of 30 ± 5%, only the electrode sample in this measurement sample was lifted vertically at a rate of 10 mm/min using a tensile compression tester, and the electrode sample was Measure the load when rising 10 mm in the vertical direction. This measurement is performed three times and the average value is calculated.
This average value is divided by the area of the overlapping part of the electrode sample and the ion exchange membrane, and the mass of the electrode sample in the part overlapping with the ion exchange membrane, and the applied force per unit mass/unit area (1) (N /mg·cm ² ).

The applied force (1) per unit mass/unit area obtained by method (i) indicates that good handling properties are obtained and that diaphragms such as ion exchange membranes and microporous membranes, deteriorated electrodes, and catalyst coatings are not used. From the viewpoint of having ^good adhesive strength with ^a power supply body that is It is preferably less than 1.5 N/(mg·cm ² ), even more preferably 1.2 N/mg·cm ² or less, and even more preferably 1.20 N/mg·cm ² or less. It is even more preferably 1.1 N/mg·cm ² or less, even more preferably 1.10 N/mg·cm ² or less, particularly preferably 1.0 N/mg·cm ² or less, and 1.00 N /mg·cm ² or less is particularly preferable. In addition, from the viewpoint of further improving electrolytic performance, it is preferably more than 0.005 N/(mg·cm ² ), more preferably 0.08 N/(mg·cm ² ) or more, and even more preferably 0.08 N/(mg·cm 2 ). 1 N/(mg cm ² ) or more, and more preferably 0.14 N/(mg ·cm ² ), and more preferably 0.2 N/(mg·cm ² ) or more.

[Method (ii)]
A nickel plate (1.2 mm thick, 200 mm square, same nickel plate as in method (i) above) obtained by blasting with alumina grain number 320 and an electrode sample (130 mm square) were laminated in this order. After thoroughly immersing this laminate in pure water, excess water adhering to the surface of the laminate is removed to obtain a measurement sample. Under conditions of a temperature of 23 ± 2°C and a relative humidity of 30 ± 5%, only the electrode sample in this measurement sample was lifted vertically at a rate of 10 mm/min using a tensile compression tester, and the electrode sample was , and measure the load when it rises 10 mm in the vertical direction. This measurement is performed three times and the average value is calculated.
This average value is divided by the area of the overlapping part of the electrode sample and the nickel plate, and the mass of the electrode sample in the part overlapping with the nickel plate, and the adhesive force per unit mass/unit area (2) (N/mg・cm ² ) is calculated.

The applied force (2) per unit mass/unit area obtained by method (ii) indicates that good handling properties are obtained and that diaphragms such as ion exchange membranes and microporous membranes, deteriorated electrodes, and catalyst coatings are not used. From the viewpoint of having ^good adhesive strength with ^a power supply body that is It is preferably less than 1.5 N/(mg·cm ² ), even more preferably 1.2 N/mg·cm ² or less, and even more preferably 1.20 N/mg·cm ² or less. It is even more preferably 1.1 N/mg·cm ² or less, even more preferably 1.10 N/mg·cm ² or less, particularly preferably 1.0 N/mg·cm ² or less, and 1.00 N /mg·cm ² or less is particularly preferable. Furthermore, from the viewpoint of further improving electrolytic performance, it is preferably more than 0.005 N/(mg·cm ² ), more preferably 0.08 N/(mg·cm ² ) or more, and still more preferably 0.08 N/(mg·cm 2 ). 1 N/(mg·cm ² ) or more, and even more preferably 0.1 N/(mg·cm 2 ) or more, and even more preferably 0. It is 14 N/(mg·cm ² ) or more.

The electrode for electrolysis in this embodiment preferably includes an electrode base material for electrolysis and a catalyst layer. The thickness (gauge thickness) of the electrode base material for electrolysis is not particularly limited, but it provides good handling properties and prevents diaphragms such as ion exchange membranes and microporous membranes, deteriorated electrodes (power feeders), and catalyst coatings. It has good adhesion strength with electrodes (power feeders) that are not covered, can be rolled into rolls, can be bent well, and can be easily handled in large sizes (for example, size 1.5m x 2.5m). From the viewpoint that From the viewpoints of handling and economy, the thickness is even more preferably 50 μm or less. Although the lower limit is not particularly limited, it is, for example, 1 μm, preferably 5 μm, and more preferably 15 μm.

In this embodiment, in order to integrate the diaphragm and the electrolytic electrode, it is preferable that a liquid be present between them. Any liquid that generates surface tension, such as water or an organic solvent, can be used as the liquid. The larger the surface tension of the liquid, the greater the force applied between the diaphragm and the electrode for electrolysis, so a liquid with a large surface tension is preferable. Examples of the liquid include the following (the numerical value in parentheses is the surface tension of the liquid at 20°C).
Hexane (20.44 mN/m), acetone (23.30 mN/m), methanol (24.00 mN/m), ethanol (24.05 mN/m), ethylene glycol (50.21 mN/m), water (72.76 mN) /m)
If the liquid has a high surface tension, the diaphragm and the electrolytic electrode tend to be easily integrated (formed into a laminate), making it easier to replace the electrode. The amount of liquid between the diaphragm and the electrolytic electrodes needs to be such that they stick to each other due to surface tension.As a result, the amount of liquid is small, so even if the laminate is mixed with the electrolytic solution after being installed in the electrolytic cell, the electrolysis itself will not be affected. will not affect.
From a practical point of view, it is preferable to use a liquid having a surface tension of 24 mN/m to 80 mN/m, such as ethanol, ethylene glycol, or water. Particularly preferred is water or an aqueous solution made alkaline by dissolving caustic soda, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, etc. in water. Moreover, surface tension can also be adjusted by including a surfactant in these liquids. By including a surfactant, the adhesion between the diaphragm and the electrolytic electrode changes, making it possible to adjust the handling properties. The surfactant is not particularly limited, and both ionic surfactants and nonionic surfactants can be used.

The electrode for electrolysis in this embodiment is not particularly limited, but has good handling properties, includes a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode (power feeder), and an electrode without catalyst coating (power feeder). From the viewpoint of having good adhesive strength with the large size ( For example, it is more preferably 95% or more from the viewpoint of ease of handling when the size is 1.5 m x 2.5 m). The upper limit is 100%.

[Method (2)]
An ion exchange membrane (170 mm square) and an electrode sample (130 mm square) are stacked in this order. At a temperature of 23 ± 2°C and a relative humidity of 30 ± 5%, the laminate was placed on the curved surface of a polyethylene pipe (outer diameter 280 mm) so that the electrode sample in the laminate was on the outside. Thoroughly immerse the pipe in pure water to remove excess water adhering to the surface of the laminate and the pipe. After 1 minute, soak the part where the ion exchange membrane (170 mm square) and the electrode sample are in close contact. Measure the area ratio (%).

Although the electrode for electrolysis in this embodiment is not particularly limited, it has good handling property, a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode (power feeder), and an electrode without catalyst coating (power feeder). It is preferable that the ratio measured by the following method (3) is 75% or more, from the viewpoint of having good adhesive strength with the body), being able to be suitably rolled into a roll, and being able to be bent well. It is more preferably 80% or more, and even more preferably 90% or more from the viewpoint of ease of handling in large sizes (for example, size 1.5 m x 2.5 m). The upper limit is 100%.
[Method (3)]
An ion exchange membrane (170 mm square) and an electrode sample (130 mm square) are stacked in this order. At a temperature of 23 ± 2°C and a relative humidity of 30 ± 5%, the laminate was placed on the curved surface of a polyethylene pipe (outer diameter 145 mm) so that the electrode sample in the laminate was on the outside. Thoroughly immerse the pipe in pure water to remove excess water adhering to the surface of the laminate and the pipe. After 1 minute, soak the part where the ion exchange membrane (170 mm square) and the electrode sample are in close contact. Measure the area ratio (%).

The electrode for electrolysis in this embodiment is not particularly limited, but has good handling properties, includes a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode (power feeder), and an electrode without catalyst coating (power feeder). It is preferable that the porous structure has a porous structure with a porosity or porosity of 5 to 90% or less, from the viewpoint of having good adhesive strength with the body) and preventing the retention of gas generated during electrolysis. The porosity is more preferably 10 to 80% or less, and even more preferably 20 to 75%.
Note that the porosity is the ratio of open pores per unit volume. There are various calculation methods depending on whether to consider the openings down to the submicron order or only the visible openings. In this embodiment, the volume V is calculated from the values of the gauge thickness, width, and length of the electrode, and the weight W is actually measured, so that the aperture ratio A can be calculated using the following formula.
A=(1-(W/(V×ρ))×100
ρ is the density (g/cm ³ ) of the electrode material. For example, in the case of nickel, it is 8.908 g/cm ³ , and in the case of titanium, it is 4.506 g/cm ³ . Adjustment of the open area ratio can be done by changing the area of punched metal per unit area for punched metal, by changing the SW (minor axis), LW (long axis), and feed values for expanded metal, or by changing the values of SW (minor axis), LW (long axis), and feed for expanded metal. For example, change the wire diameter and mesh number of metal fibers; for electroforming, change the photoresist pattern used; for non-woven fabrics, change the metal fiber diameter and fiber density; for foamed metal, create voids. It can be adjusted as appropriate by changing the mold used to make it.

From the viewpoint of handling properties, the electrode for electrolysis in this embodiment preferably has a value measured by the following method (A) of 40 mm or less, more preferably 29 mm or less, and even more preferably 10 mm or less. , even more preferably 6.5 mm or less.
[Method (A)]
Under conditions of a temperature of 23 ± 2°C and a relative humidity of 30 ± 5%, a sample of the laminate in which the ion exchange membrane and the electrolytic electrode were laminated was wound around the curved surface of a vinyl chloride core material with an outer diameter of φ32 mm. After fixing the electrolytic electrode and leaving it for 6 hours, separate the electrolytic electrode and place it on a horizontal plate. Measure the vertical heights L ₁ and L ₂ at both ends of the electrolytic electrode. The average value of is the measured value.

The electrode for electrolysis in this embodiment has a size of 50 mm x 50 mm, a temperature of 24°C, a relative humidity of 32%, a piston speed of 0.2 cm/s, and an air flow rate of 0.4 cc/cm ² /s. It is preferable that the ventilation resistance (hereinafter also referred to as "ventilation resistance 1") in the case (hereinafter also referred to as "measurement condition 1") is 24 kPa·s/m or less. High ventilation resistance means that it is difficult for air to flow, and refers to a state of high density. In this state, the products of electrolysis remain in the electrode, making it difficult for the reaction substrate to diffuse into the electrode, and thus the electrolytic performance (voltage, etc.) tends to deteriorate. Additionally, the concentration on the film surface tends to increase. Specifically, the caustic concentration tends to increase at the cathode surface, and the supply of salt water tends to decrease at the anode surface. As a result, products remain at a high concentration at the interface where the diaphragm and the electrolytic electrode are in contact, leading to damage to the diaphragm, which tends to lead to voltage increase and membrane damage on the cathode surface, and membrane damage on the anode surface. It is in.
In order to prevent these problems, it is preferable that the ventilation resistance is 24 kPa·s/m or less.
From the same viewpoint as above, it is more preferable that it is less than 0.19 kPa·s/m, even more preferably that it is 0.15 kPa·s/m or less, and even more preferably that it is 0.07 kPa·s/m or less. preferable.
Note that if the ventilation resistance is greater than a certain level, NaOH generated at the electrode in the case of a cathode tends to stay at the interface between the electrolytic electrode and the diaphragm, resulting in a high concentration, and in the case of the anode, the ability to supply salt water decreases. However, the salt water concentration tends to be low, and in order to prevent damage to the diaphragm that may occur due to such retention, it is preferably less than 0.19 kPa・s/m, and 0. It is more preferable that it is .15 kPa·s/m or less, and even more preferably that it is 0.07 kPa·s/m or less.
On the other hand, when the ventilation resistance is low, the area of the electrode for electrolysis becomes small, so the electrolysis area tends to become small and the electrolysis performance (voltage, etc.) tends to deteriorate. When the ventilation resistance is zero, since no electrode for electrolysis is installed, the power supply body functions as an electrode, and the electrolysis performance (voltage, etc.) tends to deteriorate significantly. From this point of view, the preferable lower limit value specified as ventilation resistance 1 is not particularly limited, but is preferably greater than 0 kPa·s/m, more preferably 0.0001 kPa·s/m or more, and still more preferably It is 0.001 kPa·s/m or more.
Note that, due to the measurement method, if the ventilation resistance 1 is 0.07 kPa·s/m or less, sufficient measurement accuracy may not be obtained. From this point of view, for electrodes for electrolysis whose ventilation resistance 1 is 0.07 kPa・s/m or less, the ventilation resistance (hereinafter referred to as "ventilation resistance 2) is also possible. That is, the ventilation resistance 2 is the ventilation resistance when the electrode for electrolysis has a size of 50 mm x 50 mm, the temperature is 24° C., the relative humidity is 32%, the piston speed is 2 cm/s, and the ventilation amount is 4 cc/cm ² /s.
The above-mentioned ventilation resistances 1 and 2 can be set within the above ranges by appropriately adjusting the porosity, electrode thickness, etc., which will be described later, for example. More specifically, for example, if the thickness is the same, as the porosity increases, ventilation resistances 1 and 2 tend to decrease, and as the porosity decreases, ventilation resistances 1 and 2 tend to increase. be.

Hereinafter, more specific embodiments of the electrolysis electrode in this embodiment will be described.
The electrode for electrolysis in this embodiment preferably includes an electrode base material for electrolysis and a catalyst layer. The catalyst layer may be composed of a plurality of layers or may have a single layer structure as described below.
As shown in FIG. 7, the electrolysis electrode 101 according to the present embodiment includes an electrolysis electrode base material 10 and a pair of first layers 20 that cover both surfaces of the electrolysis electrode base material 10. It is preferable that the first layer 20 covers the entire electrode base material 10 for electrolysis. This makes it easier to improve the catalytic activity and durability of the electrolytic electrode. In addition, the first layer 20 may be laminated only on one surface of the electrode base material 10 for electrolysis.
Further, as shown in FIG. 7, the surface of the first layer 20 may be covered with a second layer 30. The second layer 30 preferably covers the entire first layer 20. Moreover, the second layer 30 may be laminated only on one surface of the first layer 20.

(electrode base material for electrolysis)
The electrode base material 10 for electrolysis is not particularly limited, but for example, valve metals such as nickel, nickel alloy, stainless steel, or titanium can be used, and metals such as nickel (Ni) and titanium (Ti) can be used. It is preferable that at least one selected element is included.
Considering that when stainless steel is used in a highly concentrated alkaline aqueous solution, iron and chromium are eluted, and that the electrical conductivity of stainless steel is about 1/10 that of nickel, it is suitable as an electrode base material for electrolysis. A base material containing nickel (Ni) is preferred.
Further, when the electrode base material 10 for electrolysis is used in a highly concentrated saline solution close to saturation in an atmosphere where chlorine gas is generated, it is also preferable that the material is titanium, which has high corrosion resistance.
There is no particular limitation on the shape of the electrode base material 10 for electrolysis, and an appropriate shape can be selected depending on the purpose. As for the shape, any of punched metal, nonwoven fabric, foamed metal, expanded metal, porous metal foil formed by electroforming, so-called woven mesh made by knitting metal wires, etc. can be used. Among these, punched metal or expanded metal is preferred. Note that electroforming is a technology that combines photolithography and electroplating to produce metal thin films with precise patterns. In this method, a pattern is formed on a substrate using photoresist, and the areas not protected by the resist are electroplated to obtain a thin metal.
Regarding the shape of the electrode base material for electrolysis, there are suitable specifications depending on the distance between the anode and the cathode in the electrolytic cell. Although not particularly limited, when the anode and cathode have a finite distance, an expanded metal or punched metal shape can be used, and in the case of a so-called zero gap electrolytic cell where the ion exchange membrane and the electrode are in contact. For example, woven mesh made of thin wires, wire mesh, foamed metal, metal nonwoven fabric, expanded metal, punched metal, metal porous foil, etc. can be used.
Examples of the electrode base material 10 for electrolysis include porous metal foil, wire mesh, metal nonwoven fabric, punched metal, expanded metal, and foamed metal.
The plate material before being processed into punched metal or expanded metal is preferably a rolled plate material, electrolytic foil, or the like. It is preferable that the electrolytic foil is further plated with the same element as the base material as a post-treatment to form irregularities on one or both sides.
Further, as described above, the thickness of the electrode base material 10 for electrolysis is preferably 300 μm or less, more preferably 205 μm or less, even more preferably 155 μm or less, and even more preferably 135 μm or less. It is preferably 125 μm or less, even more preferably 120 μm or less, even more preferably 100 μm or less, and even more preferably 50 μm or less from the viewpoint of handling and economical efficiency. preferable. Although the lower limit is not particularly limited, it is, for example, 1 μm, preferably 5 μm, and more preferably 15 μm.

In the electrode base material for electrolysis, it is preferable to relieve residual stress during processing by annealing the electrode base material for electrolysis in an oxidizing atmosphere. In addition, in order to improve the adhesion with the catalyst layer coated on the surface of the electrode base material for electrolysis, irregularities are formed using steel grid, alumina powder, etc., and then the surface area is increased by acid treatment. It is preferable to increase it. Alternatively, it is preferable to perform plating treatment with the same element as the base material to increase the surface area.

It is preferable to perform a treatment to increase the surface area of the electrolysis electrode base material 10 in order to bring the first layer 20 and the surface of the electrolysis electrode base material 10 into close contact. Examples of the treatment for increasing the surface area include blasting using a cut wire, steel grid, alumina grid, etc., acid treatment using sulfuric acid or hydrochloric acid, plating treatment with the same element as the base material, and the like. The arithmetic mean surface roughness (Ra) of the substrate surface is not particularly limited, but is preferably from 0.05 μm to 50 μm, more preferably from 0.1 to 10 μm, even more preferably from 0.1 to 8 μm.

Next, a case where the electrode for electrolysis in this embodiment is used as an anode for salt electrolysis will be described.
(first layer)
In FIG. 7, the first layer 20, which is a catalyst layer, contains at least one oxide of ruthenium oxide, iridium oxide, and titanium oxide. Examples of the ruthenium oxide include RuO ₂ and the like. Examples of the iridium oxide include IrO ₂ and the like. Examples of titanium oxides include TiO ₂ and the like. Preferably, the first layer 20 includes two types of oxides, ruthenium oxide and titanium oxide, or three types of oxides, ruthenium oxide, iridium oxide, and titanium oxide. Thereby, the first layer 20 becomes a more stable layer, and the adhesion with the second layer 30 is further improved.

When the first layer 20 contains two types of oxides, ruthenium oxide and titanium oxide, the amount of titanium oxide contained in the first layer 20 per mole of ruthenium oxide contained in the first layer 20 The amount of the compound is preferably 1 to 9 mol, more preferably 1 to 4 mol. By setting the composition ratio of the two types of oxides within this range, the electrolytic electrode 101 exhibits excellent durability.

When the first layer 20 contains three types of oxides: ruthenium oxide, iridium oxide, and titanium oxide, the amount of oxide contained in the first layer 20 per mol of ruthenium oxide contained in the first layer 20 The amount of iridium oxide is preferably 0.2 to 3 mol, more preferably 0.3 to 2.5 mol. Further, the titanium oxide contained in the first layer 20 is preferably 0.3 to 8 mol, more preferably 1 to 7 mol, per 1 mol of ruthenium oxide contained in the first layer 20. preferable. By setting the composition ratio of the three types of oxides within this range, the electrolytic electrode 101 exhibits excellent durability.

When the first layer 20 contains at least two types of oxides selected from ruthenium oxide, iridium oxide, and titanium oxide, these oxides preferably form a solid solution. By forming an oxide solid solution, the electrolytic electrode 101 exhibits excellent durability.

In addition to the above compositions, various compositions can be used as long as they contain at least one oxide of ruthenium oxide, iridium oxide, and titanium oxide. For example, it is also possible to use as the first layer 20 an oxide coating called DSA® containing ruthenium, iridium, tantalum, niobium, titanium, tin, cobalt, manganese, platinum, etc.

The first layer 20 does not need to be a single layer and may include multiple layers. For example, the first layer 20 may include a layer containing three types of oxides and a layer containing two types of oxides. The thickness of the first layer 20 is preferably 0.05 to 10 μm, more preferably 0.1 to 8 μm.

(Second layer)
Preferably, the second layer 30 contains ruthenium and titanium. This makes it possible to further lower the chlorine overvoltage immediately after electrolysis.

Preferably, the second layer 30 contains palladium oxide, a solid solution of palladium oxide and platinum, or an alloy of palladium and platinum. Thereby, the chlorine overvoltage immediately after electrolysis can be further lowered.

The thicker the second layer 30 is, the longer the electrolytic performance can be maintained; however, from the economical point of view, the thickness is preferably 0.05 to 3 μm.

Next, a case where the electrode for electrolysis in this embodiment is used as a cathode for salt electrolysis will be described.
(first layer)
Components of the first layer 20, which is a catalyst layer, include C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru. , Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb , Dy, Ho, Er, Tm, Yb, Lu, and oxides or hydroxides of the metals.
It may or may not contain at least one of a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, and an alloy containing a platinum group metal.
When containing at least one of a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, and an alloy containing a platinum group metal, a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, a platinum group metal Preferably, the metal-containing alloy contains at least one platinum group metal selected from platinum, palladium, rhodium, ruthenium, and iridium.
The platinum group metal preferably includes platinum.
The platinum group metal oxide preferably includes ruthenium oxide.
The platinum group metal hydroxide preferably includes ruthenium hydroxide.
The platinum group metal alloy preferably includes an alloy of platinum, nickel, iron, or cobalt.
Furthermore, it is preferable to include an oxide or hydroxide of a lanthanoid element as a second component, if necessary. As a result, the electrolysis electrode 101 exhibits excellent durability.
The oxide or hydroxide of the lanthanoid element preferably contains at least one selected from lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, and dysprosium.
Furthermore, it is preferable to include a transition metal oxide or hydroxide as a third component, if necessary.
By adding the third component, the electrolysis electrode 101 exhibits better durability and the electrolysis voltage can be reduced.
Examples of preferred combinations include ruthenium only, ruthenium + nickel, ruthenium + cerium, ruthenium + lanthanum, ruthenium + lanthanum + platinum, ruthenium + lanthanum + palladium, ruthenium + praseodymium, ruthenium + praseodymium + platinum, ruthenium + praseodymium + platinum + Palladium, ruthenium + neodymium, ruthenium + neodymium + platinum, ruthenium + neodymium + manganese, ruthenium + neodymium + iron, ruthenium + neodymium + cobalt, ruthenium + neodymium + zinc, ruthenium + neodymium + gallium, ruthenium + neodymium + sulfur, ruthenium + Neodymium + lead, ruthenium + neodymium + nickel, ruthenium + neodymium + copper, ruthenium + samarium, ruthenium + samarium + manganese, ruthenium + samarium + iron, ruthenium + samarium + cobalt, ruthenium + samarium + zinc, ruthenium + samarium + gallium, Ruthenium + samarium + sulfur, ruthenium + samarium + lead, ruthenium + samarium + nickel, platinum + cerium, platinum + palladium + cerium, platinum + palladium + lanthanum + cerium, platinum + iridium, platinum + palladium, platinum + iridium + palladium, Examples include platinum + nickel + palladium, platinum + nickel + ruthenium, alloys of platinum and nickel, alloys of platinum and cobalt, and alloys of platinum and iron.
When the catalyst does not contain a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, or an alloy containing a platinum group metal, it is preferable that the main component of the catalyst is nickel element.
It is preferable that at least one of nickel metal, oxide, and hydroxide is included.
A transition metal may be added as a second component. The second component to be added preferably contains at least one element selected from titanium, tin, molybdenum, cobalt, manganese, iron, sulfur, zinc, copper, and carbon.
Preferred combinations include nickel + tin, nickel + titanium, nickel + molybdenum, nickel + cobalt, and the like.
If necessary, an intermediate layer can be provided between the first layer 20 and the electrode base material 10 for electrolysis. By providing the intermediate layer, the durability of the electrolytic electrode 101 can be improved.
The intermediate layer is preferably one that has affinity with both the first layer 20 and the electrode base material 10 for electrolysis. As the intermediate layer, nickel oxides, platinum group metals, platinum group metal oxides, and platinum group metal hydroxides are preferred. The intermediate layer can be formed by coating and baking a solution containing the components that form the intermediate layer, or by heat-treating the base material at a temperature of 300 to 600°C in an air atmosphere to oxidize the surface. A material layer can also be formed. In addition, it can be formed by a known method such as a thermal spraying method or an ion plating method.

(Second layer)
Components of the second layer 30, which is a catalyst layer, include C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru. , Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb , Dy, Ho, Er, Tm, Yb, Lu, and oxides or hydroxides of the metals.
It may or may not contain at least one of a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, and an alloy containing a platinum group metal. Examples of preferable combinations of elements contained in the second layer include the combinations listed for the first layer. The combination of the first layer and the second layer may be a combination of the same composition but different composition ratios, or a combination of different compositions.

As for the thickness of the catalyst layer, the total thickness of the formed catalyst layer and intermediate layer is preferably 0.01 μm to 20 μm. If it is 0.01 μm or more, it can fully function as a catalyst. If it is 20 μm or less, it is possible to form a strong catalyst layer with less falling off from the base material. More preferably 0.05 μm to 15 μm. More preferably, it is 0.1 μm to 10 μm. More preferably, it is 0.2 μm to 8 μm.

The thickness of the electrode, that is, the total thickness of the electrode base material for electrolysis and the catalyst layer, is preferably 315 μm or less, more preferably 220 μm or less, even more preferably 170 μm or less, and even more preferably 150 μm or less, from the viewpoint of electrode handling properties. It is more preferably 145 μm or less, particularly preferably 140 μm or less, even more preferably 138 μm or less, and even more preferably 135 μm or less. If it is 135 μm or less, particularly good handling properties can be obtained. Further, from the same viewpoint as above, the diameter is preferably 130 μm or less, more preferably less than 130 μm, even more preferably 120 μm or less, even more preferably 115 μm or less, and still more preferably 65 μm. It is as follows. The lower limit is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more from a practical standpoint, and more preferably 20 μm or more. The thickness of the electrode can be determined by measuring with a Digimatic Sixth Gauge (Mitutoyo Co., Ltd., minimum display: 0.001 mm). The thickness of the electrode base material for electrodes is measured in the same manner as the electrode thickness. The catalyst layer thickness can be determined by subtracting the thickness of the electrolytic electrode base material from the electrode thickness.

In this embodiment, from the viewpoint of ensuring sufficient electrolytic performance, the electrolytic electrodes include Ru, Rh, Pd, Ir, Pt, Au, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ag, Ta, W, Re, Os, Al, In, Sn, Sb, Ga, Ge, B, C, N, O, Si, P, S, La, Ce, Pr, It is preferable that at least one catalyst component selected from the group consisting of Nd, Pm, Sm, Eu, Gd, Tb and Dy is included.

In this embodiment, when the electrolytic electrode is an electrode with a wide elastic deformation region, better handling properties are obtained, and there is no diaphragm such as an ion exchange membrane or microporous membrane, no deteriorated electrode, and no catalyst coating. From the viewpoint of having better adhesive strength with the power supply etc., the thickness of the electrolytic electrode is preferably 315 μm or less, more preferably 220 μm or less, even more preferably 170 μm or less, even more preferably 150 μm or less, and particularly preferably 145 μm or less. , more preferably 140 μm or less, even more preferably 138 μm or less, even more preferably 135 μm or less. If it is 135 μm or less, particularly good handling properties can be obtained. Furthermore, from the same viewpoint as above, the thickness is preferably 130 μm or less, more preferably less than 130 μm, even more preferably 115 μm or less, and even more preferably 65 μm or less. The lower limit is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more from a practical standpoint, and more preferably 20 μm or more. In addition, in this embodiment, "the elastic deformation area is wide" means that the electrode for electrolysis is wound to form a wound body, and after the winding state is released, warping due to the winding is unlikely to occur. . Moreover, the thickness of the electrolytic electrode refers to the combined thickness of the electrolytic electrode base material and the catalyst layer when the catalyst layer described below is included.

In addition, as the first electrode for electrolysis, one that functions as a cathode can be appropriately selected and used from among the electrodes for electrolysis having the materials, shapes, physical properties, etc. described above. Moreover, as the second electrode for electrolysis, an electrode that functions as an anode can be appropriately selected and used from among the electrodes for electrolysis having the materials, shapes, physical properties, etc. described above.

(Method for manufacturing electrodes for electrolysis)
Next, an embodiment of a method for manufacturing the electrolysis electrode 101 will be described in detail.
In this embodiment, the first layer 20, preferably the second layer, is formed on the electrode base material for electrolysis by a method such as baking (pyrolysis) of the coating film in an oxygen atmosphere, or ion plating, plating, or thermal spraying. By forming the electrode 30, the electrode 101 for electrolysis can be manufactured. In the manufacturing method of this embodiment, high productivity of the electrolytic electrode 101 can be achieved. Specifically, a catalyst layer is formed on the electrode base material for electrolysis through a coating process of applying a coating liquid containing a catalyst, a drying process of drying the coating liquid, and a thermal decomposition process of thermally decomposing the coating liquid. Here, thermal decomposition means heating a metal salt as a precursor to decompose it into a metal or metal oxide and a gaseous substance. Although the decomposition products vary depending on the type of metal used, the type of salt, the atmosphere in which the thermal decomposition is carried out, etc., many metals tend to form oxides in an oxidizing atmosphere. In the industrial manufacturing process of electrodes, pyrolysis is usually carried out in air and metal oxides or metal hydroxides are often formed.

(Formation of first layer of anode)
(Coating process)
The first layer 20 is formed by applying a solution (first coating liquid) in which at least one metal salt of ruthenium, iridium, and titanium is dissolved to an electrode base material for electrolysis, and then thermally decomposing (baking) it in the presence of oxygen. can be obtained. The contents of ruthenium, iridium, and titanium in the first coating liquid are approximately equal to those in the first layer 20.

The metal salt may be in any form such as chloride salt, nitrate, sulfate, metal alkoxide, or others. The solvent for the first coating liquid can be selected depending on the type of metal salt, and water, alcohols such as butanol, etc. can be used. As the solvent, water or a mixed solvent of water and alcohols is preferred. The total metal concentration in the first coating solution in which metal salts are dissolved is not particularly limited, but is preferably in the range of 10 to 150 g/L in view of the thickness of the coating film formed by one coating.

Methods for applying the first coating liquid onto the electrolytic electrode base material 10 include a dip method in which the electrolytic electrode base material 10 is immersed in the first coating liquid, a method in which the first coating liquid is applied with a brush, and a method in which the first coating liquid is applied with a brush. A roll method using a sponge-like roll impregnated with , an electrostatic coating method in which the electrolytic electrode base material 10 and the first coating liquid are charged to opposite charges and sprayed are used. Among these, the roll method or electrostatic coating method is preferred because of its excellent industrial productivity.

(drying process, pyrolysis process)
After applying the first coating liquid to the electrode base material 10 for electrolysis, it is dried at a temperature of 10 to 90°C, and thermally decomposed in a firing furnace heated to 350 to 650°C. Temporary calcination may be performed at 100 to 350°C between drying and thermal decomposition, if necessary. The drying, calcining, and thermal decomposition temperatures can be appropriately selected depending on the composition and solvent type of the first coating liquid. The longer the thermal decomposition time is, the more preferable it is, but from the viewpoint of electrode productivity, it is preferably 3 to 60 minutes, and more preferably 5 to 20 minutes.

The coating (first layer 20) is formed to a predetermined thickness by repeating the above cycle of coating, drying, and pyrolysis. After forming the first layer 20, if necessary, the stability of the first layer 20 can be further improved by performing post-heating by firing for a longer time.

(Formation of second layer)
The second layer 30 is formed as necessary, for example, after applying a solution containing a palladium compound and a platinum compound or a solution containing a ruthenium compound and a titanium compound (second coating liquid) on the first layer 20, Obtained by thermal decomposition in the presence of oxygen.

(Formation of first layer of cathode using pyrolysis method)
(Coating process)
The first layer 20 is obtained by applying a solution (first coating liquid) in which various combinations of metal salts are dissolved to an electrode base material for electrolysis, and then thermally decomposing (baking) the solution in the presence of oxygen. The metal content in the first coating liquid is approximately equal to that in the first layer 20.

The metal salt may be in any form such as chloride salt, nitrate, sulfate, metal alkoxide, or others. The solvent for the first coating liquid can be selected depending on the type of metal salt, and water, alcohols such as butanol, etc. can be used. As the solvent, water or a mixed solvent of water and alcohols is preferred. The total metal concentration in the first coating solution in which metal salts are dissolved is not particularly limited, but is preferably in the range of 10 to 150 g/L in view of the thickness of the coating film formed by one coating.

Methods for applying the first coating liquid onto the electrolytic electrode base material 10 include a dip method in which the electrolytic electrode base material 10 is immersed in the first coating liquid, a method in which the first coating liquid is applied with a brush, and a method in which the first coating liquid is applied with a brush. A roll method using a sponge-like roll impregnated with , an electrostatic coating method in which the electrolytic electrode base material 10 and the first coating liquid are charged to opposite charges and sprayed are used. Among these, the roll method or electrostatic coating method is preferred because of its excellent industrial productivity.

(drying process, pyrolysis process)
After the first coating liquid is applied to the electrode base material 10 for electrolysis, it is dried at a temperature of 10 to 90°C and thermally decomposed in a firing furnace heated to 350 to 650°C. Temporary calcination may be performed at 100 to 350°C between drying and thermal decomposition, if necessary. The drying, calcining, and thermal decomposition temperatures can be appropriately selected depending on the composition and solvent type of the first coating liquid. The longer the thermal decomposition time per cycle, the more preferable it is, but from the viewpoint of electrode productivity, it is preferably 3 to 60 minutes, more preferably 5 to 20 minutes.

The coating, drying and thermal decomposition cycles described above are repeated to form a coating (first layer 20) to a predetermined thickness. After forming the first layer 20, if necessary, the stability of the first layer 20 can be further improved by performing post-heating by firing for a longer time.

(Formation of intermediate layer)
The intermediate layer is formed as necessary, and is obtained, for example, by applying a solution containing a palladium compound or a platinum compound (second coating liquid) onto the substrate and then thermally decomposing it in the presence of oxygen. Alternatively, the nickel oxide intermediate layer may be formed on the surface of the substrate simply by heating the substrate without applying a solution.

(Formation of first layer of cathode by ion plating)
The first layer 20 can also be formed by ion plating.
One example is a method in which a base material is fixed in a chamber and a metal ruthenium target is irradiated with an electron beam. The evaporated metallic ruthenium particles are positively charged in the plasma within the chamber and deposited on the negatively charged substrate. The plasma atmosphere is argon and oxygen, and ruthenium is deposited on the substrate as ruthenium oxide.

(Formation of first layer of cathode by plating)
The first layer 20 can also be formed by a plating method.
As an example, when electrolytic plating is performed in an electrolytic solution containing nickel and tin using the base material as a cathode, a nickel and tin alloy plating can be formed.

(Formation of first layer of cathode by thermal spraying)
The first layer 20 can also be formed by thermal spraying.
As an example, a catalyst layer containing a mixture of metallic nickel and nickel oxide can be formed by plasma spraying nickel oxide particles onto a substrate.

Hereinafter, the ion exchange membrane according to one embodiment of the diaphragm will be described in detail.
[Ion exchange membrane]
The ion exchange membrane is not particularly limited as long as it can be formed into a laminate with an electrolytic electrode, and various ion exchange membranes can be used. In this embodiment, an ion exchange membrane is used that has a membrane body containing a hydrocarbon polymer or a fluorine-containing polymer having an ion exchange group, and a coating layer provided on at least one surface of the membrane body. It is preferable. Further, the coating layer preferably contains inorganic particles and a binder, and has a specific surface area of 0.1 to 10 m ² /g. Ion exchange membranes with such a structure tend to exhibit stable electrolytic performance with less influence on electrolytic performance by gases generated during electrolysis.
The above-mentioned perfluorocarbon polymer membrane into which an ion exchange group has been introduced refers to a sulfonic acid having an ion exchange group derived from a sulfo group (a group represented by -SO ₃ -, hereinafter also referred to as a "sulfonic acid group"). and a carboxylic acid layer having an ion exchange group derived from a carboxyl group (a group represented by -CO ₂ -, hereinafter also referred to as a "carboxylic acid group"). From the viewpoint of strength and dimensional stability, it is preferable to further include a reinforcing core material.
The inorganic particles and the binder will be described in detail in the section of the description of the coating layer below.

FIG. 8 is a schematic cross-sectional view showing one embodiment of an ion exchange membrane. The ion exchange membrane 1 has a membrane body 1a containing a hydrocarbon polymer or a fluorine-containing polymer having ion exchange groups, and coating layers 11a and 11b formed on both sides of the membrane body 1a.

In the ion exchange membrane 1, the membrane main body 1a includes a sulfonic acid layer 3 having an ion exchange group derived from a sulfo group (a group represented by -SO ₃ ^- , hereinafter also referred to as a "sulfonic acid group"), and a sulfonic acid layer 3 having an ion exchange group derived from a sulfo group (a group represented by -SO 3 -, hereinafter also referred to as "sulfonic acid group"), A carboxylic acid layer 2 having an ion exchange group (a group represented by -CO ₂ ^- , hereinafter also referred to as a "carboxylic acid group"), and the strength and dimensional stability are enhanced by a reinforcing core material 4. . Since the ion exchange membrane 1 includes a sulfonic acid layer 3 and a carboxylic acid layer 2, it is suitably used as a cation exchange membrane.

Note that the ion exchange membrane may have only one of a sulfonic acid layer and a carboxylic acid layer. Further, the ion exchange membrane does not necessarily need to be reinforced with a reinforcing core material, and the arrangement of the reinforcing core material is not limited to the example shown in FIG. 8.

(Membrane body)
First, the membrane main body 1a that constitutes the ion exchange membrane 1 will be explained.
The membrane body 10 may be any material as long as it has a function of selectively permeating cations and contains a hydrocarbon polymer or a fluorine-containing polymer having an ion exchange group, and its structure and material are not particularly limited. However, a suitable one can be selected as appropriate.

The hydrocarbon polymer or fluorine-containing polymer having an ion exchange group in the membrane body 1a is, for example, a hydrocarbon polymer or a fluorine-containing polymer having an ion exchange group precursor that can become an ion exchange group by hydrolysis or the like. It can be obtained from merging. Specifically, for example, the main chain is made of a fluorinated hydrocarbon, has a group (ion exchange group precursor) that can be converted into an ion exchange group by hydrolysis etc. as a pendant side chain, and is melt processable. After producing a precursor of the membrane main body 1a using a polymer (hereinafter referred to as "fluorine-containing polymer (a)" in some cases), the membrane is formed by converting the ion exchange group precursor into an ion exchange group. A main body 1a can be obtained.

The fluorine-containing polymer (a) includes, for example, at least one monomer selected from the following first group, and at least one monomer selected from the following second group and/or the following third group. It can be produced by copolymerization. Further, it can also be produced by homopolymerization of one type of monomer selected from the following first group, the following second group, and the following third group.

Examples of the first group of monomers include vinyl fluoride compounds. Examples of the vinyl fluoride compound include vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, perfluoroalkyl vinyl ether, and the like. In particular, when the ion exchange membrane is used as a membrane for alkaline electrolysis, the vinyl fluoride compound is preferably a perfluoromonomer, and the vinyl fluoride compound is preferably a perfluoromonomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, and perfluoroalkyl vinyl ether. Fluoromonomers are preferred.

Examples of the second group of monomers include vinyl compounds having a functional group that can be converted into a carboxylic acid type ion exchange group (carboxylic acid group). Examples of vinyl compounds having a functional group that can be converted into a carboxylic acid group include monomers represented by CF ₂ =CF(OCF ₂ CYF) _s -O(CZF) _t -COOR (herein, , s represents an integer of 0 to 2, t represents an integer of 1 to 12, Y and Z each independently represent F or _CF3 , R represents a lower alkyl group.The lower alkyl group is , for example, an alkyl group having 1 to 3 carbon atoms).

Among these, a compound represented by CF ₂ =CF(OCF ₂ CYF) _n -O(CF ₂ ) _m -COOR is preferred. Here, n represents an integer of 0 to 2, m represents an integer of 1 to 4, Y represents F or CF ₃ , and R represents CH ₃ , C ₂ H ₅ or C ₃ H ₇ .

In addition, when the ion exchange membrane is used as a cation exchange membrane for alkaline electrolysis, it is preferable to use at least a perfluoro compound as a monomer, but the alkyl group of the ester group (see R above) becomes heavy at the time of hydrolysis. The alkyl group (R) does not have to be a perfluoroalkyl group in which all hydrogen atoms are substituted with fluorine atoms because it is lost in combination.

Among the above monomers, the monomers shown below are more preferable as the second group of monomers.
CF ₂ =CFOCF ₂ -CF(CF ₃ )OCF ₂ COOCH ₃ ,
CF ₂ =CFOCF ₂ CF(CF ₃ )O(CF ₂ ) ₂ COOCH ₃ ,
CF ₂ =CF[OCF ₂ -CF(CF ₃ )] ₂ O(CF ₂ ) ₂ COOCH ₃ ,
CF ₂ =CFOCF ₂ CF(CF ₃ )O(CF ₂ ) ₃ COOCH ₃ ,
CF ₂ =CFO(CF ₂ ) ₂ COOCH ₃ ,
_{CF2 =} CFO( _CF2 ) _3COOCH3 .

Examples of the third group of monomers include vinyl compounds having a functional group that can be converted into a sulfone-type ion exchange group (sulfonic acid group). As the vinyl compound having a functional group that can be converted into a sulfonic acid group, for example, a monomer represented by CF ₂ =CFO-X-CF ₂ -SO ₂ F (where X is a perfluoroalkylene group) is preferable. ). Specific examples of these include the monomers shown below.
CF ₂ =CFOCF ₂ CF ₂ SO ₂ F,
_{CF2 = CFOCF2CF} ( _CF3 ) _{OCF2CF2SO2F ,
CF2 = CFOCF2CF ( CF3} ) _{OCF2CF2CF2SO2F ,
CF2} =CF _{( CF2} ) _2SO2F ,
CF ₂ =CFO [CF ₂ CF (CF ₃ ) O] ₂ CF ₂ CF ₂ SO ₂ F,
_{CF2 = CFOCF2CF ( CF2OCF3} ) _{OCF2CF2SO2F .}

Among these, _{CF2 = CFOCF2CF} ( _{CF3 ) OCF2CF2CF2SO2F} and _CF2 = _{CFOCF2CF ( CF3} ) _{OCF2CF2SO2F are} more _preferable .

Copolymers obtained from these monomers can be produced by polymerization methods developed for the homopolymerization and copolymerization of fluorinated ethylene, and in particular by the general polymerization methods used for tetrafluoroethylene. . For example, in the non-aqueous method, an inert solvent such as perfluorohydrocarbon or chlorofluorocarbon is used in the presence of a radical polymerization initiator such as perfluorocarbon peroxide or an azo compound at a temperature of 0 to 200°C and a pressure of 0. The polymerization reaction can be carried out under conditions of 1 to 20 MPa.

In the above copolymerization, the types and proportions of the combinations of the monomers are not particularly limited, and are selected and determined depending on the types and amounts of functional groups desired to be imparted to the resulting fluorine-containing polymer. For example, in the case of producing a fluorine-containing polymer containing only carboxylic acid groups, at least one monomer from each of the first group and the second group may be selected and copolymerized. Furthermore, in the case of producing a fluorine-containing polymer containing only sulfonic acid groups, at least one monomer from each of the first group and third group may be selected and copolymerized. Furthermore, when preparing a fluorine-containing polymer having a carboxylic acid group and a sulfonic acid group, at least one monomer is selected from each of the monomers of the first group, the second group, and the third group. All you have to do is polymerize. In this case, the desired fluorine-containing system can also be obtained by separately polymerizing the copolymer consisting of the first group and the second group and the copolymer consisting of the first group and the third group, and then mixing them together. Polymers can be obtained. The mixing ratio of each monomer is not particularly limited, but if the amount of functional groups per unit polymer is increased, the ratio of monomers selected from the second group and the third group may be increased. good.

The total ion exchange capacity of the fluorine-containing copolymer is not particularly limited, but is preferably 0.5 to 2.0 mg equivalent/g, more preferably 0.6 to 1.5 mg equivalent/g. Here, the total ion exchange capacity refers to the equivalent amount of exchange groups per unit weight of dry resin, and can be measured by neutralization titration or the like.

In the membrane body 1a of the ion exchange membrane 1, a sulfonic acid layer 3 containing a fluorine-containing polymer having a sulfonic acid group and a carboxylic acid layer 2 containing a fluorine-containing polymer having a carboxylic acid group are laminated. There is. By providing the membrane main body 1a with such a layered structure, the selective permeability of cations such as sodium ions can be further improved.

When the ion exchange membrane 1 is placed in an electrolytic cell, the sulfonic acid layer 3 is usually placed on the anode side of the electrolytic cell, and the carboxylic acid layer 2 is placed on the cathode side of the electrolytic cell.

The sulfonic acid layer 3 is preferably made of a material with low electrical resistance, and is preferably thicker than the carboxylic acid layer 2 from the viewpoint of film strength. The thickness of the sulfonic acid layer 3 is preferably 2 to 25 times that of the carboxylic acid layer 2, more preferably 3 to 15 times.

It is preferable that the carboxylic acid layer 2 has high anion exclusion properties even if it is thin. The anion-excluding property herein refers to the property of preventing anions from entering or permeating the ion exchange membrane 1. In order to improve the anion exclusion property, it is effective to arrange a carboxylic acid layer with a small ion exchange capacity in place of the sulfonic acid layer.

As the fluorine-containing polymer used for the sulfonic acid layer 3, for example, a polymer obtained using CF ₂ =CFOCF ₂ CF (CF ₃ )OCF ₂ CF ₂ SO ₂ F as the third group monomer is used. suitable.

Examples of the fluorine-containing polymer used in the carboxylic acid layer 2 include a polymer obtained using CF ₂ =CFOCF ₂ CF(CF ₂ )O(CF ₂ ) ₂ COOCH ₃ as the second group monomer. is suitable.

(coating layer)
The ion exchange membrane preferably has a coating layer on at least one side of the membrane body. Further, as shown in FIG. 8, in the ion exchange membrane 1, coating layers 11a and 11b are formed on both surfaces of the membrane body 1a, respectively.
The coating layer includes inorganic particles and a binder.

The average particle size of the inorganic particles is more preferably 0.90 μm or more. When the average particle size of the inorganic particles is 0.90 μm or more, durability against not only gas adhesion but also impurities is extremely improved. That is, a particularly remarkable effect can be obtained by increasing the average particle size of the inorganic particles and satisfying the above-mentioned specific surface area value. In order to satisfy such average particle diameter and specific surface area, irregularly shaped inorganic particles are preferable. Inorganic particles obtained by melting and inorganic particles obtained by crushing ore can be used. Preferably, inorganic particles obtained by pulverizing raw stones can be suitably used.

Further, the average particle size of the inorganic particles can be 2 μm or less. If the average particle size of the inorganic particles is 2 μm or less, the film can be prevented from being damaged by the inorganic particles. The average particle size of the inorganic particles is more preferably 0.90 to 1.2 μm.

Here, the average particle size can be measured using a particle size distribution meter ("SALD2200" manufactured by Shimadzu Corporation).

The shape of the inorganic particles is preferably irregular. Resistance to impurities is further improved. Further, the particle size distribution of the inorganic particles is preferably broad.

The inorganic particles may contain at least one inorganic substance selected from the group consisting of oxides of Group IV elements of the Periodic Table, nitrides of Group IV elements of the Periodic Table, and carbides of Group IV elements of the Periodic Table. preferable. More preferred are zirconium oxide particles from the viewpoint of durability.

These inorganic particles are inorganic particles manufactured by crushing ore of inorganic particles, or by melting and refining the ore of inorganic particles, spherical particles with uniform particle diameters are made into inorganic particles. Preferably they are particles.

The raw stone pulverization method includes, but is not particularly limited to, a ball mill, a bead mill, a colloid mill, a conical mill, a disk mill, an edge mill, a flour mill, a hammer mill, a pellet mill, a VSI mill, a Willie mill, a roller mill, a jet mill, and the like. Further, it is preferable to wash the powder after pulverization, and in this case, acid treatment is preferable as the washing method. Thereby, impurities such as iron adhering to the surface of the inorganic particles can be reduced.

Preferably, the coating layer includes a binder. The binder is a component that holds inorganic particles on the surface of the ion exchange membrane to form a coating layer. It is preferable that the binder contains a fluorine-containing polymer from the viewpoint of resistance to electrolyte solutions and products caused by electrolysis.

As the binder, a fluorine-containing polymer having a carboxylic acid group or a sulfonic acid group is preferable from the viewpoint of resistance to electrolytic solution and products caused by electrolysis and adhesion to the surface of the ion exchange membrane. preferable. When a coating layer is provided on a layer containing a fluoropolymer having a sulfonic acid group (sulfonic acid layer), it is more preferable to use a fluoropolymer having a sulfonic acid group as a binder for the coating layer. . Furthermore, when a coating layer is provided on a layer containing a fluoropolymer having a carboxylic acid group (carboxylic acid layer), a fluoropolymer having a carboxylic acid group may be used as a binder for the coating layer. More preferred.

The content of inorganic particles in the coating layer is preferably 40 to 90% by mass, more preferably 50 to 90% by mass. Further, the content of the binder is preferably 10 to 60% by mass, more preferably 10 to 50% by mass.

The distribution density of the coating layer in the ion exchange membrane is preferably 0.05 to 2 mg/cm ² . Further, when the ion exchange membrane has an uneven surface, the distribution density of the coating layer is preferably 0.5 to 2 mg/cm ² .

The method for forming the coating layer is not particularly limited, and any known method can be used. For example, a method may be used in which a coating liquid in which inorganic particles are dispersed in a solution containing a binder is applied by spraying or the like.

(Reinforced core material)
Preferably, the ion exchange membrane has a reinforcing core disposed inside the membrane body.

The reinforcing core material is a member that enhances the strength and dimensional stability of the ion exchange membrane. By arranging the reinforcing core material inside the membrane main body, the expansion and contraction of the ion exchange membrane can be particularly controlled within a desired range. Such an ion exchange membrane does not expand or contract more than necessary during electrolysis or the like, and can maintain excellent dimensional stability over a long period of time.

The structure of the reinforcing core material is not particularly limited, and may be formed by spinning a thread called reinforcing thread, for example. The reinforcing thread here is a member that constitutes the reinforcing core material, and is capable of imparting desired dimensional stability and mechanical strength to the ion exchange membrane, and can stably exist in the ion exchange membrane. It refers to thread. By using a reinforcing core material obtained by spinning such reinforcing yarns, it is possible to impart even better dimensional stability and mechanical strength to the ion exchange membrane.

The materials for the reinforcing core material and the reinforcing thread used therein are not particularly limited, but they are preferably materials that are resistant to acids and alkalis, and since long-term heat resistance and chemical resistance are required, fluorine-containing materials are preferred. Fibers made of polymers are preferred.

Examples of the fluorine-containing polymer used for the reinforcing core material include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-ethylene copolymer (ETFE). , tetrafluoroethylene-hexafluoropropylene copolymer, trifluorochloroethylene-ethylene copolymer, and vinylidene fluoride polymer (PVDF). Among these, it is preferable to use fibers made of polytetrafluoroethylene, especially from the viewpoint of heat resistance and chemical resistance.

The diameter of the reinforcing yarn used in the reinforcing core material is not particularly limited, but is preferably 20 to 300 deniers, more preferably 50 to 250 deniers. The weaving density (number of threads per unit length) is preferably 5 to 50 threads/inch. The form of the reinforcing core material is not particularly limited, and for example, woven fabric, nonwoven fabric, knitted fabric, etc. can be used, but the form of woven fabric is preferable. Further, the thickness of the woven fabric used is preferably 30 to 250 μm, more preferably 30 to 150 μm.

As the woven or knitted fabric, monofilament, multifilament, yarn thereof, slit yarn, etc. can be used, and various weaving methods such as plain weaving, entwining weaving, knitting weaving, cord weaving, and shear sukkah can be used.

The weaving method and arrangement of the reinforcing core material in the membrane body are not particularly limited, and can be appropriately arranged in consideration of the size and shape of the ion exchange membrane, the desired physical properties of the ion exchange membrane, the usage environment, etc. .

For example, the reinforcing core material may be arranged along one predetermined direction of the membrane body, but from the viewpoint of dimensional stability, the reinforcing core material may be arranged along a predetermined first direction, and the first Preferably, another reinforcing core is arranged along a second direction that is substantially perpendicular to the direction. By arranging a plurality of reinforcing core materials substantially perpendicularly inside the membrane body in the longitudinal direction of the membrane body, it is possible to provide even better dimensional stability and mechanical strength in multiple directions. For example, it is preferable to weave reinforcing core materials (warp threads) arranged along the longitudinal direction and reinforcing core materials (weft threads) arranged along the transverse direction on the surface of the membrane main body. Plain weave is created by weaving the warp and weft threads in alternating ups and downs, entanglement weave is created by twisting two warp threads and interweaving them with the weft thread, and weaving is created by aligning two or several warp threads with the same number of weft threads. Nanakoori or the like is more preferable from the viewpoints of dimensional stability, mechanical strength, and ease of manufacture.

In particular, it is preferable that the reinforcing core material is arranged along both the MD direction (Machine Direction direction) and the TD direction (Transverse Direction direction) of the ion exchange membrane. That is, it is preferable that the fabric is plain woven in the MD direction and the TD direction. Here, the MD direction refers to the direction (flow direction) in which the membrane body and various core materials (e.g., reinforced core material, reinforced yarn, sacrificial yarn described later) are conveyed in the ion exchange membrane manufacturing process described later. The TD direction refers to a direction substantially perpendicular to the MD direction. The yarn woven along the MD direction is referred to as MD yarn, and the yarn woven along the TD direction is referred to as TD yarn. Usually, the ion exchange membrane used for electrolysis has a rectangular shape, and the longitudinal direction is often the MD direction, and the width direction is often the TD direction. By weaving a reinforcing core material that is an MD yarn and a reinforcing core material that is a TD yarn, it is possible to provide even more excellent dimensional stability and mechanical strength in multiple directions.

The arrangement interval of the reinforcing core material is not particularly limited, and can be appropriately arranged in consideration of the desired physical properties of the ion exchange membrane, usage environment, etc.

The aperture ratio of the reinforcing core material is not particularly limited, and is preferably 30% or more, more preferably 50% or more and 90% or less. The aperture ratio is preferably 30% or more from the viewpoint of electrochemical properties of the ion exchange membrane, and preferably 90% or less from the viewpoint of the mechanical strength of the ion exchange membrane.

The aperture ratio of the reinforcing core material is the total surface area through which substances such as ions (electrolytic solution and cations contained therein (e.g., sodium ions)) can pass through in the area (A) of either surface of the membrane body. It refers to the ratio (B/A) of area (B). The total surface area (B) through which substances such as ions can pass is the total area of the ion exchange membrane where cations, electrolytes, etc. are not blocked by the reinforcing core material contained in the ion exchange membrane. can.

FIG. 9 is a schematic diagram for explaining the aperture ratio of the reinforcing core material constituting the ion exchange membrane. FIG. 9 is an enlarged view of a part of the ion exchange membrane, showing only the arrangement of the reinforcing core materials 21a and 21b within the area, and illustration of other members is omitted.

The reinforced core material is a region surrounded by the reinforced core material 21a arranged along the vertical direction and the reinforced core material 21b arranged in the horizontal direction, and is calculated from the area (A) of the region including the area of the reinforced core material. By subtracting the total area (C) of the area (A), the total area (B) of the area through which substances such as ions can pass can be determined. That is, the aperture ratio can be determined by the following formula (I).
Aperture ratio = (B) / (A) = ((A) - (C)) / (A) ... (I)

Among the reinforcing core materials, from the viewpoint of chemical resistance and heat resistance, tape yarns or highly oriented monofilaments containing PTFE are particularly preferred. Specifically, a tape yarn made by slitting a high-strength porous sheet made of PTFE into a tape shape, or a highly oriented monofilament made of PTFE of 50 to 300 denier is used, and the weave density is 10 to 50 pieces per yarn. It is more preferable that the reinforcing core material is a plain weave with a thickness of 50 to 100 μm. It is more preferable that the ion exchange membrane including such a reinforcing core material has an aperture ratio of 60% or more.

Examples of the shape of the reinforcing thread include round thread, tape-like thread, and the like.

(Communication hole)
The ion exchange membrane preferably has communication holes inside the membrane body.

The communication hole refers to a hole that can serve as a flow path for ions and electrolyte generated during electrolysis. Further, the communicating hole is a tubular hole formed inside the membrane main body, and is formed by elution of a sacrificial core material (or sacrificial thread) to be described later. The shape, diameter, etc. of the communication hole can be controlled by selecting the shape and diameter of the sacrificial core material (sacrificial yarn).

By forming communicating holes in the ion exchange membrane, mobility of the electrolytic solution can be ensured during electrolysis. Although the shape of the communication hole is not particularly limited, it can be made into the shape of the sacrificial core material used to form the communication hole according to the manufacturing method described below.

The communicating holes are preferably formed so as to alternately pass through the anode side (sulfonic acid layer side) and the cathode side (carboxylic acid layer side) of the reinforced core material. With this structure, in the part where the communication hole is formed on the cathode side of the reinforced core material, ions (for example, sodium ions) transported through the electrolyte filled in the communication hole are transferred to the reinforced core material. It can also flow to the cathode side. As a result, since the flow of cations is not blocked, the electrical resistance of the ion exchange membrane can be further lowered.

The communication holes may be formed along only one predetermined direction of the membrane body constituting the ion exchange membrane, but from the viewpoint of achieving more stable electrolytic performance, the communication holes may be formed along the vertical and horizontal directions of the membrane body. It is preferable that the grooves are formed in both directions.

〔Production method〕
A preferred method for producing an ion exchange membrane includes a method having the following steps (1) to (6).
(1) Step: A step of producing a fluorine-containing polymer having an ion exchange group or an ion exchange group precursor that can become an ion exchange group by hydrolysis.
(2) Process: If necessary, by weaving at least a plurality of reinforcing core materials and a sacrificial yarn that has the property of dissolving in acid or alkali and forms communication holes, adjacent reinforcing core materials can be bonded together. The process of obtaining reinforcement with sacrificial threads placed between them.
(3) Step: A step of forming a film from the fluorine-containing polymer having an ion exchange group or an ion exchange group precursor that can become an ion exchange group by hydrolysis.
(4) Step: A step of embedding the reinforcing material in the film as necessary to obtain a membrane body in which the reinforcing material is disposed inside.
(5) Step: A step of hydrolyzing the membrane body obtained in step (4) (hydrolysis step).
(6) Step: A step of providing a coating layer on the membrane body obtained in step (5) (coating step).

Each step will be explained in detail below.

(1) Step: Step of producing a fluorine-containing polymer In the step (1), a fluorine-containing polymer is produced using the raw material monomers listed in the first to third groups above. In order to control the ion exchange capacity of the fluorine-containing polymer, the mixing ratio of the raw material monomers may be adjusted in the production of the fluorine-containing polymer forming each layer.

(2) Process: Manufacturing process of reinforcing material The reinforcing material is a woven fabric etc. woven with reinforcing threads. A reinforcing material is embedded within the membrane to form a reinforced core. When forming an ion exchange membrane with communicating holes, sacrificial threads are also woven into the reinforcing material. In this case, the amount of sacrificial yarn mixed is preferably 10 to 80% by mass, more preferably 30 to 70% by mass of the entire reinforcing material. By weaving sacrificial yarn, it is also possible to prevent the reinforcing core material from shifting.

The sacrificial thread is soluble in the membrane manufacturing process or in an electrolytic environment, and rayon, polyethylene terephthalate (PET), cellulose, polyamide, and the like are used. Also preferred is polyvinyl alcohol having a thickness of 20 to 50 deniers and consisting of monofilament or multifilament.

In addition, in step (2), by adjusting the arrangement of the reinforcing core material and the sacrificial yarn, the aperture ratio, arrangement of the communicating holes, etc. can be controlled.

(3) Step: Film-forming step (3) In the step, the fluorine-containing polymer obtained in step (1) is formed into a film using an extruder. The film may have a single-layer structure, a two-layer structure of a sulfonic acid layer and a carboxylic acid layer as described above, or a multi-layer structure of three or more layers.

Examples of methods for forming a film include the following.
A method for separately forming films of a fluoropolymer having a carboxylic acid group and a fluoropolymer having a sulfonic acid group.
A method of forming a composite film by coextruding a fluoropolymer having a carboxylic acid group and a fluoropolymer having a sulfonic acid group.

Note that the number of films may be plural. Further, coextruding different types of films is preferable because it contributes to increasing the adhesive strength at the interface.

(4) Process: Obtaining the membrane body (4) In the step (4), the reinforcing material obtained in step (2) is embedded inside the film obtained in step (3), thereby forming the membrane body in which the reinforcing material is embedded. obtain.

A preferred method for forming the membrane body includes (i) a fluorine-containing polymer having a carboxylic acid group precursor (for example, a carboxylic acid ester functional group) located on the cathode side (hereinafter, a layer consisting of this will be referred to as the first layer); and a fluorine-containing polymer having a sulfonic acid group precursor (for example, a sulfonyl fluoride functional group) (hereinafter, a layer consisting of this will be referred to as the second layer) are formed into a film by a coextrusion method, and if necessary, a heating source and Using a vacuum source, the reinforcing material and the second layer/first layer composite film are laminated in this order on a flat plate or drum with a large number of pores on the surface, with an air-permeable, heat-resistant release paper interposed therebetween. (ii) Separately from the second layer/first layer composite film, a method of integrating each polymer while removing air between each layer under a temperature at which each polymer melts; The fluoropolymer (third layer) is made into a film alone in advance, and a heat-resistant, air-permeable film is formed on a flat plate or drum with many pores on the surface using a heating source and a vacuum source as necessary. The third layer film, reinforcing core material, and composite film consisting of the second layer/first layer are laminated in this order via release paper, and the air between each layer is removed under reduced pressure at a temperature where each polymer melts. One method is to integrate the two.

Here, coextruding the first layer and the second layer contributes to increasing the adhesive strength at the interface.

Moreover, the method of integrating under reduced pressure has a feature that the thickness of the third layer on the reinforcing material becomes larger than that of the pressure pressing method. Furthermore, since the reinforcing material is fixed to the inner surface of the membrane main body, the ion exchange membrane has the ability to maintain sufficient mechanical strength.

Note that the variations in lamination described here are just examples, and after considering the layer structure and physical properties of the desired membrane body, select a suitable lamination pattern (for example, a combination of each layer, etc.), and then perform coextrusion. can do.

In addition, in order to further improve the electrical performance of the ion exchange membrane, a third layer made of a fluorine-containing polymer having both a carboxylic acid group precursor and a sulfonic acid group precursor is added between the first layer and the second layer. It is also possible to further interpose four layers, or to use a fourth layer made of a fluorine-containing polymer having both a carboxylic acid group precursor and a sulfonic acid group precursor instead of the second layer.

The fourth layer may be formed by separately producing a fluorine-containing polymer having a carboxylic acid group precursor and a fluorine-containing polymer having a sulfonic acid group precursor, and then mixing them. A method using a copolymer of a monomer having a group precursor and a monomer having a sulfonic acid group precursor may be used.

When the fourth layer is configured as an ion exchange membrane, a coextrusion film of the first layer and the fourth layer is formed, and the third layer and the second layer are separately formed into films, and the above-mentioned The layers may be laminated by a method, or the three layers of the first layer/fourth layer/second layer may be formed into a film by coextrusion.

In this case, the direction in which the extruded film flows is the MD direction. In this way, a membrane body containing a fluorine-containing polymer having ion exchange groups can be formed on the reinforcing material.

Further, it is preferable that the ion exchange membrane has a protruding portion, that is, a convex portion, made of a fluorine-containing polymer having a sulfonic acid group on the surface side made of the sulfonic acid layer. The method for forming such convex portions is not particularly limited, and any known method for forming convex portions on the resin surface can be employed. Specifically, for example, a method of embossing the surface of the membrane body can be mentioned. For example, when integrating the above-described composite film and the reinforcing material, etc., the above-mentioned convex portions can be formed by using a release paper that has been embossed in advance. When forming convex portions by embossing, the height and arrangement density of the convex portions can be controlled by controlling the emboss shape (shape of release paper) to be transferred.

(5) Hydrolysis step In the (5) step, the membrane body obtained in the step (4) is hydrolyzed to convert the ion exchange group precursor into an ion exchange group (hydrolysis step).

Furthermore, in step (5), elution holes can be formed in the membrane body by dissolving and removing the sacrificial thread contained in the membrane body with acid or alkali. Note that the sacrificial thread may remain in the communication hole without being completely dissolved and removed. Further, the sacrificial thread remaining in the communication hole may be dissolved and removed by an electrolytic solution when the ion exchange membrane is subjected to electrolysis.

The sacrificial thread is soluble in acid or alkali during the manufacturing process of the ion exchange membrane or in an electrolytic environment, and when the sacrificial thread is eluted, communication holes are formed in the region.

Step (5) can be carried out by immersing the membrane body obtained in step (4) in a hydrolysis solution containing an acid or an alkali. As the hydrolysis solution, for example, a mixed solution containing KOH and DMSO (dimethyl sulfoxide) can be used.

The mixed solution preferably contains 2.5 to 4.0N of KOH and 25 to 35% by mass of DMSO.

The hydrolysis temperature is preferably 70 to 100°C. The higher the temperature, the thicker the apparent thickness can be. More preferably, the temperature is 75 to 100°C.

The hydrolysis time is preferably 10 to 120 minutes. The longer the time, the thicker the apparent thickness can be. More preferably, it is 20 to 120 minutes.

Here, the process of forming communicating holes by eluting the sacrificial thread will be described in more detail. FIGS. 10(a) and 10(b) are schematic diagrams for explaining a method of forming communicating holes in an ion exchange membrane.

In FIGS. 10A and 10B, only the reinforcing thread 52, the sacrificial thread 504a, and the communication hole 504 formed by the sacrificial thread 504a are shown, and other members such as the membrane main body are not shown. ing.

First, the reinforcing yarn 52 that will constitute the reinforcing core material in the ion exchange membrane and the sacrificial yarn 504a for forming the communicating holes 504 in the ion exchange membrane are used as a braided reinforcing material. Then, in step (5), the sacrificial thread 504a is eluted to form the communication hole 504.

According to the above method, it is simple because the way the reinforcing threads 52 and the sacrificial threads 504a are woven can be adjusted depending on the arrangement of the reinforcing core material and the communicating holes in the membrane body of the ion exchange membrane.

In FIG. 10(a), a plain weave reinforcing material is illustrated in which reinforcing threads 52 and sacrificial threads 504a are woven along both the longitudinal and lateral directions on the page. The arrangement of the sacrificial thread 504a can be changed.

(6) Coating process In the (6) process, a coating liquid containing inorganic particles obtained by crushing or melting the raw stone and a binder is prepared, and the coating liquid is applied to the ion exchange membrane obtained in the step (5). A coating layer can be formed by applying it to a surface and drying it.

As a binder, a fluorine-containing polymer having an ion exchange group precursor is hydrolyzed with an aqueous solution containing dimethyl sulfoxide (DMSO) and potassium hydroxide (KOH), and then immersed in hydrochloric acid to bind the ion exchange groups. A binder in which ions are substituted with H ⁺ (for example, a fluorine-containing polymer having a carboxyl group or a sulfo group) is preferred. This is preferable because it becomes easier to dissolve in water and ethanol, which will be described later.

The binder is dissolved in a solution of water and ethanol. Note that the volume ratio of water to ethanol is preferably 10:1 to 1:10, more preferably 5:1 to 1:5, and even more preferably 2:1 to 1:2. Inorganic particles are dispersed in the solution thus obtained using a ball mill to obtain a coating solution. At this time, the average particle diameter of the particles can also be adjusted by adjusting the time and rotation speed during dispersion. Note that the preferred blending amounts of the inorganic particles and the binder are as described above.

The concentrations of the inorganic particles and binder in the coating liquid are not particularly limited, but it is preferable to use a thin coating liquid. This makes it possible to uniformly coat the surface of the ion exchange membrane.

Further, when dispersing the inorganic particles, a surfactant may be added to the dispersion liquid. As the surfactant, nonionic surfactants are preferred, such as NOF Corporation's HS-210, NS-210, P-210, and E-212.

An ion exchange membrane can be obtained by applying the obtained coating liquid to the surface of the ion exchange membrane by spray coating or roll coating.

[Microporous membrane]
As mentioned above, the microporous membrane of this embodiment is not particularly limited as long as it can be formed into a laminate with an electrode for electrolysis, and various microporous membranes can be applied.
The porosity of the microporous membrane of this embodiment is not particularly limited, but may be, for example, 20 to 90, preferably 30 to 85. The above porosity can be calculated using the following formula, for example.
Porosity = (1 - (Dry membrane weight) / (Volume calculated from membrane thickness, width, and length and weight calculated from membrane material density)) x 100
The average pore diameter of the microporous membrane of this embodiment is not particularly limited, but can be, for example, 0.01 μm to 10 μm , preferably 0.05 μm to 5 μm. The above average pore diameter can be determined, for example, by cutting the membrane perpendicularly to the thickness direction and observing the cut surface using FE-SEM. It can be determined by measuring the diameter of the observed pores at about 100 points and averaging them.
The thickness of the microporous membrane of this embodiment is not particularly limited, but can be, for example, 10 μm to 1000 μm, preferably 50 μm to 600 μm. The above thickness can be measured using, for example, a micrometer (manufactured by Mitutoyo Co., Ltd.).
Specific examples of the above-mentioned microporous membrane include Zirfon Perl UTP 500 manufactured by Agfa (also referred to as Zirfon membrane in this embodiment), International Publication No. 2013-183584 pamphlet, and International Publication No. 2016-203701 pamphlet. Examples include those described in .

In this embodiment, the diaphragm preferably includes a first ion exchange resin layer and a second ion exchange resin layer having a different EW (ion exchange equivalent) from that of the first ion exchange resin layer. . Moreover, it is preferable that the diaphragm includes a first ion exchange resin layer and a second ion exchange resin layer having a different functional group from that of the first ion exchange resin layer. The ion exchange equivalent can be adjusted depending on the functional group to be introduced, and the functional groups that can be introduced are as described above.

(water electrolysis)
The electrolytic cell of this embodiment, which is used for water electrolysis, has a configuration in which the ion exchange membrane in the electrolytic cell used for salt electrolysis described above is replaced with a microporous membrane. Further, the present invention is different from the electrolytic cell used for the above-mentioned salt electrolysis in that the raw material to be supplied is water. Regarding other configurations, the electrolytic cell for water electrolysis can also have the same structure as the electrolytic cell for salt electrolysis. In the case of salt electrolysis, chlorine gas is generated in the anode chamber, so titanium is used as the material for the anode chamber, but in the case of water electrolysis, oxygen gas is only generated in the anode chamber, so the cathode chamber is made of titanium. The same material can be used. For example, nickel etc. can be mentioned. Further, as the anode coating, a catalyst coating for oxygen generation is suitable. Examples of catalytic coatings include platinum group metals and transition metals , oxides, hydroxides, and the like. For example, elements such as platinum, iridium, palladium, ruthenium, nickel, cobalt, iron, etc. can be used.

[Manufacturing method of electrolytic cell]
The method for manufacturing an electrolytic cell according to the present embodiment includes an anode (hereinafter also referred to as "existing anode"), a cathode facing the anode (hereinafter also referred to as "existing cathode"), and an anode and a cathode. a diaphragm disposed between the two (hereinafter also referred to as "existing diaphragm"); a first elastic body (hereinafter also referred to as "existing elastic body") that presses the cathode in the direction toward the anode; A method for manufacturing a new electrolytic cell from an existing electrolytic cell comprising: a first electrolytic electrode disposed between the diaphragm and the cathode; (A) disposing a second elastic body between the first electrolysis electrode and the cathode, the second elastic body pressing the first electrolysis electrode in a direction toward the anode; do.
As described above, according to the method for manufacturing an electrolytic cell according to the present embodiment, not only can the performance of the cathode be updated without removing the cathode (that is, the existing cathode in the existing electrolytic cell), but also the first This makes it possible to replace parts to maintain the zero gap structure without removing the elastic body of the existing electrolytic cell (i.e., the existing elastic body in the existing electrolytic cell). Improves work efficiency when replacing parts in an electrolytic cell without the need for complicated work such as removing the elastic body, installing and fixing a new elastic body, installing and fixing a new electrode, and transporting and installing it in the electrolytic cell. can be done.

In this embodiment, the existing electrolytic cell includes an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, and a first diaphragm that presses the cathode in a direction toward the anode. In other words, it includes an electrolytic cell. The existing electrolytic cell is not particularly limited as long as it includes the above-mentioned constituent members, and various known structures can be applied to the existing electrolytic cell. Note that when the anode in the existing electrolytic cell is in contact with the second electrolysis electrode described later, it essentially functions as a power supply, and when it is not in contact with the second electrolysis electrode, it functions as a power supply itself. functions as an anode. Similarly, when the cathode in an existing electrolytic cell is in contact with the first electrolytic electrode, it essentially functions as a power supply, and when it is not in contact with the first electrolytic electrode, it functions as a power supply itself. It functions as a cathode. Here, in this embodiment and a second embodiment described later, the power supply body means a deteriorated electrode (that is, an existing electrode), an electrode without catalyst coating, or the like.

In this embodiment, the new electrolytic cell further includes a second elastic body and a first electrolytic electrode in addition to the members already functioning as an anode or a cathode in the existing electrolytic cell, and the entire electrolytic cell From the viewpoint of renewal, it preferably further includes a laminate including a second elastic body, a first electrolytic electrode, and a new diaphragm, and more preferably a laminate including a second elastic body and a first electrolytic electrode. The apparatus further includes a laminate including an electrode for electrolysis, a new diaphragm, and a second electrode for electrolysis. In other words, the first electrolytic electrode placed when manufacturing a new electrolytic cell functions as a cathode, and the second electrolytic electrode functions as an anode, and these are used in existing electrolytic cells. The cathode and anode are separate bodies. In this embodiment, even if the electrolytic performance of the electrolytic electrode functioning as an anode and/or cathode deteriorates due to operation of an existing electrolytic cell, the deteriorated electrolytic electrode can be replaced with a new electrolytic electrode separate from the electrolytic cell. By replacing the electrode with an electrode for electrolysis, the performance of the anode and/or cathode can be updated. Furthermore, when the above-described laminate is used, the existing diaphragm is replaced with a new diaphragm, so that the performance of the diaphragm whose performance has deteriorated due to operation can be updated at the same time. In this embodiment and the second embodiment described later, "updating" means updating the performance of each part in the electrolytic cell, and more specifically, before the existing electrolytic cell is put into operation. It means to make the performance equivalent to the initial performance, or to make it higher than the initial performance.

In this embodiment, the existing electrolytic cell is assumed to be "an electrolytic cell that has already been put into operation", and the new electrolytic cell is assumed to be "an electrolytic cell which is not yet put into operation". In other words, once an electrolytic cell manufactured as a new electrolytic cell is put into operation, it becomes the "existing electrolytic cell in this embodiment", and the existing electrolytic cell with a new laminate is "the new electrolytic cell in this embodiment". "An electrolytic cell."

In this embodiment, the diaphragm in the existing electrolytic cell and the new diaphragm can be the same in shape, material, and physical properties. Therefore, in this specification, "the diaphragm in this embodiment" includes "a new diaphragm in this embodiment".

(Process (A))
An example for implementing step (A) in this embodiment will be described using FIG. 11. As shown in FIG. 11A, in the existing electrolytic cell, the cation exchange membrane 51 is sandwiched between the cathode 21 side of one electrolytic cell 50 and the anode 11 side of the other electrolytic cell 50. Here, for example, by operating a press in the existing electrolytic cell, the sandwiching is released and a gap S is formed between the cathode 21 and the cation exchange membrane 51 as shown in FIG. 11(B). Can be done. Next, the second elastic body 22' and the first electrolytic electrode 53 are arranged in this gap S, and these are sandwiched by operating the press again, etc., to obtain the state shown in FIG. 11(C). be able to. That is, in the state shown in FIG. 11(C), the first electrolysis electrode 53 is disposed between the cation exchange membrane 51 and the cathode 21, and the first electrolysis electrode 53 and the cathode 21 are A second elastic body 22' is disposed between them. Note that in the state shown in FIG. 11C, the first electrolysis electrode 53 functions as a cathode electrode, and the first electrolysis electrode 53, the second elastic body 22', the cathode 21, and a not-shown It will be electrically connected to the first elastic body 22 (see FIG. 3).
The order in which the first electrolysis electrode 53 and the second elastic body 22' are arranged is not particularly limited, and they may be arranged at the same time, or one of them may be arranged first.

(Process (B))
An example for implementing step (B) in this embodiment will be described using FIG. 12. As shown in FIG. 12(A), in the existing electrolytic cell, the cation exchange membrane 51 is sandwiched between the cathode 21 side of one electrolytic cell 50 and the anode 11 side of the other electrolytic cell 50. Here, the sandwiching is released by, for example, operating a press in the existing electrolytic cell, and as shown in FIG. A gap S can be formed between the exchange membrane 51 and the exchange membrane 51, respectively. Next, the second elastic body 22' and the first electrolytic electrode 53 are placed in the gap S on the cathode 21 side, the second electrolytic electrode 53' is placed in the gap S on the anode 11 side, and pressed again. By manipulating the container or the like, these can be held and brought into the state shown in FIG. 12(C). That is, in the state shown in FIG. 12(C), the first electrolysis electrode 53 is disposed between the cation exchange membrane 51 and the cathode 21, and the first electrolysis electrode 53 and the cathode 21 are A second elastic body 22' is disposed between the anode 11 and the cation exchange membrane 51, and a second electrolysis electrode 53' is disposed between the anode 11 and the cation exchange membrane 51. Note that in the state shown in FIG. 12(C), the first electrolytic electrode 53 functions as a cathode electrode, the second electrolytic electrode 53' functions as an anode electrode, and the second electrolytic electrode 53' functions as an anode electrode. The electrode 53' and the anode 11 are electrically connected, and the first electrolytic electrode 53, the second elastic body 22', the cathode 21, and the first elastic body 22 (not shown) are connected. It will be electrically connected.
The order in which the first electrolysis electrode 53, the second elastic body 22', and the second electrolysis electrode 53' are arranged is not particularly limited, and they may be arranged at the same time, or one of them may be arranged first. You may.

(Sub-steps (a1) to (a2))
In this embodiment, from the viewpoint of overall updating, step (A) includes a sub-step (a1) of removing the diaphragm, and after the sub-step (a1), a new diaphragm and the first electrolytic electrode are added. It is preferable to include a sub-step (a2) of disposing a laminate comprising the above between the second elastic body and the anode. Here, an example for implementing sub-steps (a1) to (a2) will be described using FIG. 13. As shown in FIG. 13(A), in the existing electrolytic cell, the cation exchange membrane 51 is sandwiched between the cathode 21 side of one electrolytic cell 50 and the anode 11 side of the other electrolytic cell 50. Here, by releasing the sandwiching, for example by operating a press in the existing electrolytic cell, and further removing the cation exchange membrane 51, the cathode 21 and the anode 11 are separated as shown in FIG. 13(B). A gap S can be formed between them. Next, the second elastic body 22', the first electrolytic electrode 53, and the cation exchange membrane 51' as a new diaphragm are arranged in this gap S, and these are removed by operating the press again. can be held in the state shown in FIG. 13(C). That is, in the state shown in FIG. 13(C), the first electrolysis electrode 53 is disposed between the cation exchange membrane 51' and the cathode 21, and the first electrolysis electrode 53 and the cathode 21 A second elastic body 22' is disposed between the two. Note that in the state shown in FIG. 13(C), the first electrolysis electrode 53 functions as a cathode electrode, and the first electrolysis electrode 53, the second elastic body 22', the cathode 21, and a not-shown It will be electrically connected to the first elastic body 22 (see FIG. 3).
The order in which the first electrolytic electrode 53, second elastic body 22', and cation exchange membrane 51' are arranged is not particularly limited, and they may be arranged at the same time, or one of them may be arranged first. Good too. Here, when these are arranged at the same time, it is preferable to use a laminate including the first electrolysis electrode 53 and the cation exchange membrane 51'. From the viewpoint of handleability in updating operations, it is preferable that such a laminate has the same configuration or physical properties as the laminate described for the electrolytic cell of this embodiment.

In the sub-steps (a1) to (a2), when using a laminate including the first electrolytic electrode 53 and the cation exchange membrane 51', from the viewpoint of overall renewal, the laminate is Preferably, it further includes an electrolytic electrode 53'. An example of implementing the above steps will be described using FIG. 14. As shown in FIG. 14(A), in the existing electrolytic cell, the cation exchange membrane 51 is sandwiched between the cathode 21 side of one electrolytic cell 50 and the anode 11 side of the other electrolytic cell 50. Here, by releasing the sandwiching, for example by operating a press in the existing electrolytic cell, and further removing the cation exchange membrane 51, the cathode 21 and the anode 11 are separated as shown in FIG. 14(B). A gap S can be formed between them. Next, in the gap S, a laminate 54 including the first electrolysis electrode 53, a cation exchange membrane 51' as a new diaphragm, and a second electrolysis electrode 53', and a second elastic body 22' are placed. 14(C) can be obtained by disposing these and sandwiching them by operating the press again or the like. That is, in the state shown in FIG. 14(C), the first electrolytic electrode 53 is disposed between the cation exchange membrane 51' and the cathode 21, and the first electrolytic electrode 53 and the cathode 21 A second elastic body 22' is disposed between the anode 11 and the cation exchange membrane 51', and a second electrolysis electrode 53' is disposed between the anode 11 and the cation exchange membrane 51'. In addition, in the state shown in FIG. 14(C), the first electrolytic electrode 53 functions as a cathode electrode, the second electrolytic electrode 53' functions as an anode electrode, and the second electrolytic electrode 53' functions as an anode electrode. The electrode 53' and the anode 11 are electrically connected, and the first electrolytic electrode 53, the second elastic body 22', the cathode 21, and the first elastic body 22 (not shown) are connected. It will be electrically connected.
The order in which the laminate 54 and the second elastic body 22' are arranged is not particularly limited, and they may be arranged at the same time or one of them may be arranged first.

In this embodiment, from the viewpoint of effectively preventing loss of the zero gap structure due to deterioration of the first elastic body, the thickness of the second elastic body is greater than the thickness of the first elastic body. Preferably larger. From the same viewpoint, it is preferable that the normal surface pressure of the second elastic body is larger than the normal surface pressure of the first elastic body.

<Second embodiment>
Here, the second aspect of this embodiment (hereinafter also referred to as "second embodiment") will be described in detail with reference to FIGS. 15 to 20.

[Method of manufacturing electrolytic cell]
The method for manufacturing an electrolytic cell according to the second embodiment (hereinafter, unless otherwise specified, "this embodiment" in the section <Second Embodiment> means the second embodiment) (hereinafter, "this embodiment" means the second embodiment) ) is an existing electrolytic method comprising an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, and a support that directly supports the cathode. A method for manufacturing a new electrolytic cell from a tank, the method comprising: replacing the diaphragm in the existing electrolytic cell with a laminate including a new diaphragm and a first electrolytic electrode; (A) disposing an elastic body between the first electrolysis electrode and the cathode, the elastic body presses the first electrolysis electrode in a direction toward the anode, and the first electrolysis electrode The thickness of the electrolysis electrode is 120 μm or less, and the first electrolysis electrode, the elastic body, the cathode, and the support are electrically connected.
As configured as above, the method of this embodiment not only makes use of the existing structure used in narrow-gap electrolytic cells and achieves zero gap, but also updates the performance of the existing diaphragm. It also has excellent work efficiency.

The new electrolytic cell is not particularly limited as long as it can be obtained by the method of this embodiment. That is, the electrolytic cell of this embodiment can be obtained by modifying an existing electrolytic cell. The following is an explanation based on the structure of an existing electrolytic cell.

In this embodiment, the new electrolytic cell is an electrolytic cell that is an existing electrolytic cell (narrow-gap electrolytic cell) made into a zero-gap electrolytic cell, and is not yet in operation. Furthermore, the existing electrolytic cell is assumed to be "an electrolytic cell that has already been put into operation" and has a configuration as described below.

[Existing electrolyzer]
In this embodiment, the existing electrolytic cell includes an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, and a support that directly supports the cathode. In other words, it is equipped with an electrolytic cell including at least an anode, a cathode, a diaphragm, and a support. The existing electrolytic cell is not particularly limited as long as it includes the above-mentioned constituent members, and various known structures can be applied to the existing electrolytic cell.

Moreover, the new electrolytic cell in this embodiment can also be said to include a new electrolytic cell obtained by modifying an electrolytic cell (existing electrolytic cell) in an existing electrolytic cell. As described above, since a new electrolytic cell is obtained when manufacturing a new electrolytic cell in this embodiment, the method for manufacturing an electrolytic cell according to this embodiment is similar to the method for manufacturing an electrolytic cell (a new electrolytic cell). More specifically, the method for manufacturing an electrolytic cell according to the present embodiment includes an anode, a cathode facing the anode, and a method for manufacturing an electrolytic cell between the anode and the cathode. A method for manufacturing a new electrolytic cell from an existing electrolytic cell comprising a diaphragm disposed on a diaphragm and a support directly supporting the cathode, the method comprising: A step (A) of replacing the diaphragm with a laminate including a diaphragm and a first electrolysis electrode, and disposing an elastic body between the first electrolysis electrode and the cathode, the elastic body comprising: The first electrolysis electrode is pressed in a direction toward the anode, the first electrolysis electrode has a thickness of 120 μm or less, the first electrolysis electrode, the elastic body, the cathode, and the support. It can be said that they are electrically connected.
From the above-mentioned viewpoint, the following explanation regarding the method for manufacturing an electrolytic cell according to the present embodiment can be read as an explanation regarding the method for manufacturing an electrolytic cell.

Hereinafter, one embodiment of an existing electrolytic cell will be described in detail, taking as an example a case where salt electrolysis is performed using an ion exchange membrane as a diaphragm. However, in this embodiment, the existing electrolytic cell and the new electrolytic cell are not limited to being used for salt electrolysis, but may also be used for water electrolysis and fuel cells, for example.

[Electrolytic cell]
First, an example of an electrolytic cell that can be used as a structural unit of an electrolytic cell in this embodiment will be described.
FIG. 15 is a schematic cross-sectional view of the electrolytic cell 50.
As shown in FIG. 15, the electrolytic cell 50 includes a cation exchange membrane 51, an anode chamber 60 defined by the cation exchange membrane 51 and the anode frame 24, and an anode chamber 60 defined by the cation exchange membrane 51 and the cathode frame 25. The cathode chamber 70 has a cathode chamber 70, an anode 11 installed in the anode chamber 60, and a cathode 21 installed in the cathode chamber 70. , each directly supported. That is, the anode frame 24 and the cathode frame 25 function as supports for the anode 11 and the cathode 21, respectively. Further, in FIG. 15, for convenience of explanation, the cation exchange membrane 51, anode frame 24, and cathode frame 25 are shown separated, but they are in contact when placed in the electrolytic cell. However, in the existing electrolytic cell, a gap exists between the cation exchange membrane 51 and the cathode 21 in the electrolytic cell.

FIG. 16 shows the electrolytic cell 4. FIG. 17 shows the process of assembling the electrolytic cell 4.
As shown in FIG. 16, the electrolytic cell 4 is composed of a plurality of electrolytic cells 50 connected in series. That is, the electrolytic cell 4 is a bipolar electrolytic cell including a plurality of electrolytic cells 50 arranged in series. Further, as shown in FIGS. 16 and 17, the electrolytic cell 4 is assembled by arranging a plurality of electrolytic cells 50 in series and connecting them with a press 5.

Electrolytic cell 4 has an anode terminal 7 and a cathode terminal 6 connected to a power source. The anode 11 of the electrolytic cell 50 located at the end of the plurality of electrolytic cells 50 connected in series in the electrolytic cell 4 is electrically connected to the anode terminal 7 . Among the plurality of electrolytic cells 50 connected in series in the electrolytic cell 4 , the cathode 21 of the electrolytic cell located at the end opposite to the anode terminal 7 is electrically connected to the cathode terminal 6 . Current during electrolysis flows from the anode terminal 7 side toward the cathode terminal 6 via the anode and cathode of each electrolysis cell 50. Note that an electrolytic cell having only an anode chamber (anode terminal cell) and an electrolytic cell having only a cathode chamber (cathode terminal cell) may be arranged at both ends of the connected electrolytic cells 50. In this case, the anode terminal 7 is connected to the anode terminal cell arranged at one end, and the cathode terminal 6 is connected to the cathode terminal cell arranged at the other end.

When electrolyzing salt water, each anode chamber 60 is supplied with salt water, and the cathode chamber 70 is supplied with pure water or a low concentration aqueous sodium hydroxide solution. Each liquid is supplied to each electrolytic cell 50 from an electrolyte supply pipe (not shown) via an electrolyte supply hose (not shown). Further, the electrolytic solution and the products of electrolysis are recovered from an electrolytic solution recovery pipe (not shown). During electrolysis, sodium ions in salt water move from the anode chamber 60 of one electrolytic cell 50 to the cathode chamber 70 through the cation exchange membrane 51 . Therefore, the current during electrolysis flows along the direction in which the electrolytic cells 50 are connected in series. That is, the current flows from the anode chamber 60 to the cathode chamber 70 via the cation exchange membrane 51. With the electrolysis of salt water, chlorine gas is generated on the anode 11 side, and sodium hydroxide (solute) and hydrogen gas are generated on the cathode 21 side.

(Anode chamber)
The anode chamber 60 has the anode 11. Further, the anode chamber 60 is disposed above the anode side electrolyte supply section that supplies electrolyte to the anode chamber 60 and the anode side electrolyte supply section, and is disposed approximately parallel or obliquely to the anode frame 24. It is preferable to have a baffle plate and an anode-side gas-liquid separation section that is arranged above the baffle plate and separates gas from the electrolyte mixed with gas.

(anode)
As the anode 11, a metal electrode such as so-called DSA (registered trademark) can be used. DSA is a titanium-based electrode whose surface is coated with an oxide containing ruthenium, iridium, and titanium.
As for the shape, any of punched metal, nonwoven fabric, foamed metal, expanded metal, porous metal foil formed by electroforming, so-called woven mesh made by knitting metal wires, etc. can be used.

(Anode side electrolyte supply section)
The anode side electrolyte supply section supplies an electrolyte to the anode chamber 60 and is connected to an electrolyte supply pipe. The anode side electrolyte supply section is preferably arranged below the anode chamber 60. As the anode-side electrolyte supply section, for example, a pipe (dispersion pipe) having an opening formed on its surface can be used. More preferably, such a pipe is arranged along the surface of the anode 11, parallel to the bottom of the electrolytic cell. This pipe is connected to an electrolytic solution supply pipe (liquid supply nozzle) that supplies electrolytic solution into the electrolytic cell 50. The electrolytic solution supplied from the liquid supply nozzle is transported into the electrolytic cell 50 by a pipe, and is supplied into the anode chamber 60 from an opening provided on the surface of the pipe. It is preferable to arrange the pipe parallel to the bottom of the electrolytic cell along the surface of the anode 11 because the electrolyte can be uniformly supplied into the anode chamber 60.

(Anode side gas-liquid separation section)
It is preferable that the anode side gas-liquid separation section is arranged above the baffle plate. During electrolysis, the anode side gas-liquid separation section has a function of separating generated gas such as chlorine gas and electrolyte. Note that, unless otherwise specified, "upward" means the right direction in the electrolytic cell 50 in FIG. 15, and "downward" means the left direction in the electrolytic cell 50 in FIG. 15.

During electrolysis, when the generated gas and electrolyte generated in the electrolytic cell 50 become a mixed phase (gas-liquid mixed phase) and are discharged from the system, vibrations occur due to pressure fluctuations inside the electrolytic cell 50, causing physical damage to the ion exchange membrane. May cause damage. In order to suppress this, it is preferable that the electrolytic cell 50 is provided with a gas-liquid separation section on the anode side for separating gas and liquid. It is preferable that a defoaming plate for eliminating air bubbles is installed in the anode side gas-liquid separation section. When the gas-liquid multiphase flow passes through the defoaming plate, the bubbles burst and can be separated into the electrolyte and the gas. As a result, vibration during electrolysis can be prevented.

(baffle board)
It is preferable that the baffle plate is disposed above the anode side electrolyte supply section and disposed approximately parallel or obliquely to the anode frame 24. The baffle plate is a partition plate that controls the flow of electrolyte in the anode chamber 60. By providing the baffle plate, the electrolytic solution (salt water, etc.) can be internally circulated in the anode chamber 60 and its concentration can be made uniform. In order to cause internal circulation, the baffle plate is preferably arranged to separate the space near the anode 11 from the space near the anode frame 24. From this point of view, the baffle plate is preferably provided so as to face each surface of the anode 11 and the anode frame 24. In the space near the anode partitioned by the baffle plate, as electrolysis progresses, the electrolyte concentration (salt water concentration) decreases and generated gases such as chlorine gas are generated. This creates a difference in the specific gravity of gas and liquid between the space near the anode 11 partitioned by the baffle plate and the space near the anode frame 24. Utilizing this, internal circulation of the electrolyte in the anode chamber 60 can be promoted and the concentration distribution of the electrolyte in the anode chamber 60 can be made more uniform.

(Anode frame)
The anode frame 24 defines an anode chamber 60 together with the cation exchange membrane 51. As the anode frame 24, a known separator for electrolysis can be used, such as a metal plate made by welding a titanium plate.

Although not shown in FIG. 15, a current collector may be separately provided between the anode 11 and the anode frame 24 in the anode chamber 60. Such a current collector can also be made of the same material and structure as the current collector of the cathode chamber, which will be described later.

(Cathode chamber)
The cathode chamber 70 has a cathode 21. Further, like the anode chamber 60, the cathode chamber 70 preferably has a cathode-side electrolyte supply section and a cathode-side gas-liquid separation section. It should be noted that, among the parts constituting the cathode chamber 70, the description of those parts similar to the parts constituting the anode chamber 60 will be omitted.

(cathode)
Preferably, the entire surface of the cathode 21 is coated with a catalyst layer for the reduction reaction. More specifically, the cathode 21 preferably has a nickel base material and a catalyst layer covering the nickel base material. Components of the catalyst layer on the nickel base material include Ru, C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Examples include metals such as Dy, Ho, Er, Tm, Yb, and Lu, and oxides or hydroxides of the metals. Examples of methods for forming the catalyst layer include plating, alloy plating, dispersion/composite plating, CVD, PVD, thermal decomposition, and thermal spraying. These methods may be combined. The catalyst layer may have multiple layers and multiple elements as necessary. Further, the cathode 21 may be subjected to a reduction treatment if necessary. Note that as the base material of the cathode 21, nickel, nickel alloy, iron, or stainless steel plated with nickel may be used.
As for the shape, any of punched metal, nonwoven fabric, foamed metal, expanded metal, porous metal foil formed by electroforming, so-called woven mesh made by knitting metal wires, etc. can be used.

(Cathode frame)
The cathode frame 25 defines a cathode chamber 70 together with the cation exchange membrane 51. As the cathode frame 25, a known separator for electrolysis can be used, such as a metal plate made of welded nickel plates.

In this embodiment, the cathode is supported directly on the support. The term "direct support" used herein is intended to exclude a mode in which the support supports the cathode via an elastic body, which will be described later, but includes a mode in which the support supports the cathode via a current collector. Although FIG. 15 shows an example in which the cathode frame 25 functions as a support that directly supports the cathode 21, the frame defining the cathode chamber may be separate from the support in this embodiment. good.

(current collector)
As described above, a current collector (not shown) may be disposed between the cathode 21 and the cathode frame 25 in the cathode chamber 70. This tends to improve the current collection effect. The current collector is preferably made of an electrically conductive metal such as nickel, iron, copper, silver, or titanium. The current collector may be a mixture, alloy, or composite oxide of these metals. The shape of the current collector may be any shape as long as it functions as a current collector, and may be a porous plate such as a plate or a mesh.

(reverse current absorber)
In the electrolytic cell 50, a reverse current absorber (not shown) can be installed in the cathode chamber as necessary. The reverse current absorber is disposed so as to be electrically connected to the cathode, and can have a multilayer structure including a base material and a reverse current absorbing layer formed on the base material. The cathode 21 and the reverse current absorption layer may be directly connected, or may be indirectly connected via a current collector, an elastic body, a cathode frame, etc. to be described later.
A material having a redox potential less noble than the redox potential of the element for the catalyst layer of the cathode described above can be selected as the material for the reverse current absorbing layer. Examples include nickel and iron. The base material is not particularly limited as long as it is electrically conductive, and various known materials can be used.

(Anode side gasket, cathode side gasket)
The anode side gasket 12 is preferably arranged on the surface of the anode frame 24 that constitutes the anode chamber 60. Moreover, it is preferable that the cathode side gasket 13 is disposed on the surface of the cathode frame 25 that constitutes the cathode chamber 70. The anode frame 24 and the cathode frame 25 are integrated so that the anode side gasket 12 and the cathode side gasket 13 of the electrolytic cell 50 sandwich the cation exchange membrane 51 (see FIG. 15). These gaskets can provide airtightness to the connection location during the above-mentioned integration.

The gasket seals between the diaphragm and each electrode. A specific example of the gasket is a frame-shaped rubber sheet with an opening formed in the center. It is preferable that the gasket has resistance to corrosive electrolytes and generated gases, and can be used for a long period of time. Therefore, from the viewpoint of chemical resistance and hardness, vulcanized products of ethylene propylene diene rubber (EPDM rubber), ethylene propylene rubber (EPM rubber), peroxide crosslinked products, etc. are usually used as gaskets. In addition, if necessary, use a gasket whose area that comes into contact with the liquid (liquid contact part) is coated with a fluororesin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA). You can also do it. These gaskets only need to each have an opening so as not to impede the flow of the electrolytic solution, and their shapes are not particularly limited. For example, a frame-shaped gasket is pasted with adhesive or the like along the periphery of each opening of the anode frame 24 constituting the anode chamber 60 or the cathode frame 25 constituting the cathode chamber 70. For example, when connecting the anode frame 24 and the cathode frame 25 via the cation exchange membrane 51 (see FIG. 15), the cation exchange membrane 51 is sandwiched between the surfaces of the anode frame 24 and the cathode frame 25 to which the gaskets are attached. Just tighten it in shape. Thereby, leakage of the electrolytic solution, alkali metal hydroxide, chlorine gas, hydrogen gas, etc. generated by electrolysis to the outside of the electrolytic cell 50 can be suppressed.

In the manufacturing method of this embodiment, a new electrolytic cell is manufactured using the existing electrolytic cell as described above through the steps detailed below.

(Process (A))
In step (A), in the existing electrolytic cell, the diaphragm is replaced with a laminate including a new diaphragm and a first electrolytic electrode, and an elastic body is placed between the first electrolytic electrode and the cathode. Allocate.
An example for implementing step (A) will be described below with reference to FIGS. 18 and 19. In step (A), a laminate including an elastic body 22 as shown in FIG. 18(A), a new diaphragm 51' and a first electrolysis electrode 21' as shown in FIG. 18(B) is used. can do.
Note that the first electrolysis electrode in this embodiment is not particularly limited as long as it has a thickness of 120 μm or less. Further, the elastic body is not particularly limited as long as it can press the first electrolysis electrode in the direction toward the anode and can be electrically connected to the cathode. Details of the first electrolysis electrode and the elastic body will be described later.
Furthermore, the diaphragm in the existing electrolytic cell and the new diaphragm can be the same in shape, material, and physical properties. Therefore, in this specification, "the diaphragm in this embodiment" includes "a new diaphragm in this embodiment". Details of the diaphragm in this embodiment will be described later.

Taking the electrolytic cell 50 in the existing electrolytic cell in FIG. 15 as an example, by operating the press in the existing electrolytic cell, the sandwiching of the cation exchange membrane 51 is released, and the cation exchange membrane 51 is removed from the electrolytic cell 50. can be taken out. Next, by disposing the elastic body 22 shown in FIG. 18(A) on the cathode 21 and disposing the laminate shown in FIG. 18(B) on the elastic body 22, the structure shown in FIG. 19 is obtained.
In FIG. 19, for convenience of explanation, the anode 11, new diaphragm 51', first electrolysis electrode 21', and elastic body 22 are shown separated, but when placed in the electrolytic cell, these are in contact. That is, in the new electrolytic cell, there is no gap between the cation exchange membrane 51 and the cathode 21 in the electrolytic cell, and there is no gap between the first electrolytic electrode 21', the elastic body 22, the cathode 21, and the cathode frame. 25 (supporting body of the cathode 21) will be electrically connected.

The order in which the laminate including the new diaphragm 51' and the first electrolytic electrode 21' and the elastic body 22 are arranged is not particularly limited, and they may be arranged at the same time, or one of them may be arranged first. You may.

In step (A), an elastic body 22 as shown in FIG. 18(A), a new diaphragm 51' as shown in FIG. 18(C), a first electrolytic electrode 21' and a second electrolytic It is also possible to use a laminate including the electrode 11'. That is, in the method for manufacturing an electrolytic cell according to the present embodiment, the laminate further includes a second electrolytic electrode, the second electrolytic electrode functions as an anode electrode, and the second electrolytic electrode An embodiment may be adopted in which the anode and the anode are electrically connected. Further, in the method for manufacturing an electrolytic cell according to the present embodiment, the laminate further includes a second electrolytic electrode, the second electrolytic electrode functions as an anode electrode, and the second electrolytic electrode An embodiment may be adopted in which the anode and the anode are electrically connected.
Note that the second electrolysis electrode in this embodiment functions as an anode electrode, and is not particularly limited as long as it can be electrically connected to the anode. Details of the second electrolysis electrode will be described later.
When using the laminate shown in FIG. 18(C), the cation exchange membrane 51 can be taken out from the electrolytic cell 50 in the same manner as described above. Next, by disposing the elastic body 22 shown in FIG. 18(A) on the cathode 21 and disposing the laminate shown in FIG. 18(C) on the elastic body 22, the structure shown in FIG. 20 is obtained.
Also in FIG. 20, for convenience of explanation, the anode 11, second electrolytic electrode 11', new diaphragm 51', first electrolytic electrode 21', and elastic body 22 are shown separated, but the electrolytic cell , they are in contact. That is, in the new electrolytic cell, there is no gap between the cation exchange membrane 51 and the cathode 21 in the electrolytic cell, and there is no gap between the first electrolytic electrode 21', the elastic body 22, the cathode 21, and the cathode frame. 25 (supporting body of the cathode 21) will be electrically connected. Furthermore, the second electrolysis electrode 11' and the anode 11 are also electrically connected.
As described above, the new electrolytic cell in this embodiment includes an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, and a diaphragm disposed between the diaphragm and the cathode. a first electrolytic electrode disposed between the anode and the diaphragm; a second electrolytic electrode disposed between the first electrolytic electrode and the cathode; An elastic body that presses the first electrolysis electrode in a direction toward the anode, and a support that directly supports the cathode, the first electrolysis electrode functioning as a cathode electrode, and the second electrolysis electrode functioning as a cathode electrode. The electrolysis electrode functions as an anode electrode, the thickness of the first electrolysis electrode is 120 μm or less, and the first electrolysis electrode, the elastic body, the cathode, and the support are electrically connected. It is preferable that the second electrolysis electrode and the anode are electrically connected.
Further, the new electrolytic cell in this embodiment includes an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, and a diaphragm disposed between the diaphragm and the cathode. a first electrolytic electrode, a second electrolytic electrode disposed between the anode and the diaphragm, and a second electrolytic electrode disposed between the first electrolytic electrode and the cathode; an elastic body that presses the electrolysis electrode in the direction toward the anode, and a support that directly supports the cathode, the first electrolysis electrode functions as a cathode electrode, and the second electrolysis electrode The electrode functions as an anode electrode, the thickness of the first electrolysis electrode is 120 μm or less, and the first electrolysis electrode, the elastic body, the cathode, and the support are electrically connected. Preferably, the second electrolytic electrode and the anode are electrically connected.

The order in which the laminate including the new diaphragm 51', the first electrolytic electrode 21', and the second electrolytic electrode 11' and the elastic body 22 are arranged is not particularly limited, and they may be arranged at the same time. However, either one may be placed first.

In this embodiment, the new electrolytic cell includes a laminate including an elastic body, a first electrolytic electrode, and a new diaphragm, which will be described later, in addition to the diaphragm, anode, cathode, and any of the above-mentioned members in the existing electrolytic cell. From the viewpoint of overall renewal, the electrolytic device preferably further includes a laminate including an elastic body, a first electrolytic electrode, a new diaphragm, and a second electrolytic electrode. In other words, the first electrolytic electrode placed when manufacturing a new electrolytic cell functions as a cathode, and the second electrolytic electrode functions as an anode, and these are used in existing electrolytic cells. The cathode and anode are separate bodies.

The cathode in the existing electrolytic cell essentially functions as a power supply by coming into contact with the first electrolytic electrode. Similarly, when the anode in an existing electrolytic cell is in contact with the second electrolysis electrode described later, it essentially functions as a power supply, and when it is not in contact with the second electrolysis electrode, it functions as a power supply. It itself functions as an anode.

As described above, in this embodiment, when achieving a zero gap based on a narrow-gap electrolytic cell that has already been operated, it is assumed that the performance of the existing cathode and diaphragm in the narrow-gap electrolytic cell deteriorates with operation. Even in such cases, the performance of the cathode and diaphragm cannot be updated because the first electrolytic electrode, which is separate from the cathode, is made to function as a new cathode and the existing diaphragm is replaced with a new diaphragm. can. Furthermore, the first electrolytic electrode has a very thin thickness of 120 μm or less and can be easily integrated with a new diaphragm. ) can be used. The size of electrolytic cells that are widely used is, for example, about 1.5 m in length and 3 m in width, and when updating components, the work of loading and unloading components of this size tends to be complicated. By using the laminate in this embodiment, the number of times the diaphragm and electrodes are put in and taken out can be reduced, so work efficiency is greatly improved. In other words, according to the manufacturing method of this embodiment, not only can an electrolytic cell be manufactured by converting a narrow-gap electrolytic cell into a zero-gap electrolytic cell, but also the performance of the existing cathode and diaphragm can be updated, and furthermore, it can be said to be excellent in work efficiency. . Furthermore, when the laminate in this embodiment further includes a second electrolytic electrode, the performance of the anode whose performance has deteriorated due to operation can also be updated at the same time.

(elastic body)
As shown in FIGS. 19 and 20, by installing the elastic body 22 between the first electrolytic electrode 21' and the cathode 21, the first electrolytic electrode 21' is pressed against the cation exchange membrane 51. As a result, the distance between the anode 11 and the cathode 21 is shortened, and the voltage can be lowered. By lowering the voltage, the power consumption of the electrolytic cell as a whole can be significantly reduced. Moreover, by installing the elastic body 22, when the laminate according to this embodiment is installed in an electrolytic cell, the first electrolytic electrode 21' is stably held in a fixed position by the pressing pressure of the elastic body 22. can be maintained.

As the elastic body, a spring member such as a spiral spring or a coil, a cushioning mat, or the like can be used. Moreover, as the elastic body, a suitable one can be adopted as appropriate, taking into consideration the stress of pressing the ion exchange membrane. The elastic body is preferably made of an electrically conductive metal such as nickel, iron, copper, silver, or titanium.
The thickness of the elastic body is not particularly limited, and can be, for example, 0.1 mm to 15 mm, preferably 0.2 mm to 10 mm, and more preferably 0.5 mm to 7 mm.
Further, the normal surface pressure of the elastic body is not particularly limited, and can be, for example, 30 gf/cm ² to 350 gf/cm ² , preferably 40 to 300 gf/cm ² , and more preferably 50 to 250 gf/cm 2 . It is ² .

(laminate)
The laminate in this embodiment includes a diaphragm such as an ion exchange membrane or a microporous membrane and a first electrode for electrolysis, and preferably further includes a second electrode for electrolysis. Hereinafter, unless otherwise specified, the term "electrode for electrolysis" includes both the first electrode for electrolysis and the second electrode for electrolysis, and specific examples of these and the diaphragm will be described in detail.

[Electrode for electrolysis]
The electrode for electrolysis in this embodiment is preferably one that can form a laminate with the diaphragm as described above, that is, one that can be integrated with the diaphragm, and more preferably one that can be used as a wound body. .
The first electrolytic electrode is not particularly limited as long as it has a thickness of 120 μm or less, and for example, the cathode It is possible to appropriately select and use a material that functions as a material.
The second electrolytic electrode is not particularly limited, and for example, one that functions as an anode among those having the material, shape, physical properties, etc. described above as the second electrolytic electrode in the <First Embodiment> section. can be selected and used as appropriate.
That is, the material, shape, physical properties, etc. of the electrode for electrolysis in this embodiment can be appropriately selected in consideration of the step (A) in this embodiment, the structure of the electrolytic cell, etc.

The diaphragm in this embodiment is not particularly limited, but among those having the material, shape, physical properties, etc. described above as the ion exchange membrane and microporous membrane in the <First Embodiment> section, the diaphragm may be one that has the same material, shape, physical properties, etc. as the above-mentioned electrolytic electrode. Those that can form a laminate can be appropriately selected and used.

(water electrolysis)
The electrolytic cell of this embodiment, which is used for water electrolysis, has a configuration in which the ion exchange membrane in the electrolytic cell used for salt electrolysis described above is replaced with a microporous membrane. Further, the present invention is different from the electrolytic cell used for the above-mentioned salt electrolysis in that the raw material to be supplied is water. Regarding other configurations, the electrolytic cell for water electrolysis can also have the same structure as the electrolytic cell for salt electrolysis. In the case of salt electrolysis, chlorine gas is generated in the anode chamber, so titanium is used as the material for the anode chamber, but in the case of water electrolysis, oxygen gas is only generated in the anode chamber, so the cathode chamber is made of titanium. The same material can be used. For example, nickel etc. can be mentioned. Further, as the anode coating, a catalyst coating for oxygen generation is suitable. Examples of catalytic coatings include platinum group metals and transition metals , oxides, hydroxides, and the like. For example, elements such as platinum, iridium, palladium, ruthenium, nickel, cobalt, iron, etc. can be used.

This application is based on the Japanese patent application filed on February 26, 2020 (Japanese Patent Application No. 2020-030768) and the Japanese patent application filed on May 12, 2020 (Japanese Patent Application No. 2020-083726). The contents are incorporated herein by reference.

Explanation of symbols for FIGS. 1 to 6 and FIGS. 11 to 14 4... Electrolytic cell, 5... Press device, 6... Cathode terminal, 7... Anode terminal,
11... Anode, 12... Anode gasket, 13... Cathode gasket,
18... Reverse current absorber, 18a... Base material, 18b... Reverse current absorbing layer, 19... Bottom of anode chamber,
21... Cathode, 22... First elastic body, 22'... Second elastic body, 23... Current collector, 24... Support,
50... Electrolytic cell, 51... Cation exchange membrane (diaphragm), 51'... New cation exchange membrane, 53... First electrolytic electrode, 53'... Second electrolytic electrode, 54... Laminated body, S ... air gap, 60... anode chamber, 70... cathode chamber,
80... Partition wall, 90... Cathode structure for electrolysis

Explanation of symbols with respect to FIG. 7 10...electrode base material for electrolysis, 20...first layer covering the base material, 30...second layer, 101...electrode for electrolysis

Explanation of symbols for FIG. 8 1... Ion exchange membrane, 1a... Membrane body, 2... Carboxylic acid layer, 3... Sulfonic acid layer, 4... Reinforced core material, 11a, 11b... Coating layer

Explanation of symbols for FIG. 9 21a, 21b...Reinforced core material

Explanation of symbols with respect to FIG. 10 52... Reinforced thread, 504... Communication hole, 504a... Sacrificial thread

Explanation of symbols for FIGS. 15 to 20 4... Electrolytic cell, 5... Press device, 6... Cathode terminal, 7... Anode terminal,
11... Anode, 11'... Second electrolysis electrode, 12... Anode gasket, 13... Cathode gasket,
21... Cathode, 21'... First electrode for electrolysis, 22... Elastic body,
24... Anode frame (anode support), 25... Cathode frame (cathode support),
50... Electrolytic cell, 51... Cation exchange membrane (diaphragm), 51'... New diaphragm (cation exchange membrane)
60...Anode chamber, 70...Cathode chamber

Claims (10)

an anode;
a cathode facing the anode;
a diaphragm disposed between the anode and the cathode;
a first elastic body that presses the cathode in a direction toward the anode;
a first electrolytic electrode disposed between the diaphragm and the cathode;
a second elastic body disposed between the first electrolysis electrode and the cathode and pressing the first electrolysis electrode in a direction toward the anode;
a current collector disposed on a surface of the first elastic body opposite to the cathode;
a support disposed on a surface of the current collector opposite to the first elastic body;
a partition wall disposed on a surface of the support body opposite to the current collector;
Equipped with
The first electrolysis electrode functions as a cathode electrode,
An electrolytic cell in which the first electrolysis electrode, the second elastic body, the cathode, and the first elastic body are electrically connected. The electrolytic cell according to claim 1, wherein the thickness of the second elastic body is greater than the thickness of the first elastic body. The electrolytic cell according to claim 1 or 2, wherein the normal surface pressure of the second elastic body is larger than the normal surface pressure of the first elastic body. further comprising a second electrolysis electrode disposed between the anode and the diaphragm,
The second electrolysis electrode functions as an anode electrode,
The electrolytic cell according to any one of claims 1 to 3, wherein the second electrolysis electrode and the anode are electrically connected. an anode, a cathode facing the anode, a diaphragm disposed between the anode and the cathode, a first elastic body that presses the cathode in a direction toward the anode, and the first elastic body a current collector disposed on a surface opposite to the cathode; a support disposed on a surface of the current collector opposite to the first elastic body; A method for manufacturing a new electrolytic cell from an existing electrolytic cell comprising: a partition wall disposed on the opposite side of the current collector;
In the existing electrolytic cell, a step of disposing a first electrolysis electrode between the diaphragm and the cathode, and disposing a second elastic body between the first electrolysis electrode and the cathode. (A) includes;
the second elastic body presses the first electrolysis electrode in a direction toward the anode,
The first electrolysis electrode functions as a cathode electrode,
A method for manufacturing an electrolytic cell, wherein the first electrolysis electrode, the second elastic body, the cathode, and the first elastic body are electrically connected. The method for manufacturing an electrolytic cell according to claim 5, wherein the second elastic body has a thickness greater than the first elastic body. The method for manufacturing an electrolytic cell according to claim 5 or 6, wherein the normal surface pressure of the second elastic body is larger than the normal surface pressure of the first elastic body. further comprising a step (B) of disposing a second electrolysis electrode between the anode and the diaphragm,
The second electrolysis electrode functions as an anode electrode,
The method for manufacturing an electrolytic cell according to any one of claims 5 to 7, wherein the second electrolysis electrode and the anode are electrically connected. The step (A) includes a sub-step (a1) of removing the diaphragm, and after the sub-step (a1), a laminate including a new diaphragm and the first electrolytic electrode is removed from the second electrode. The method for manufacturing an electrolytic cell according to any one of claims 5 to 7, comprising a sub-step (a2) of disposing the elastic body between the elastic body and the anode. The laminate further includes a second electrolysis electrode,
The second electrolysis electrode functions as an anode electrode,
The method for manufacturing an electrolytic cell according to claim 9, wherein the second electrolysis electrode and the anode are electrically connected.

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